JPH03225789A - Electromagnetic induction heating device - Google Patents

Abstract

PURPOSE:To vary the heating speed of a thin plate by winding coils in parallel to magnetic pole segments which are arrayed in parallel to the cross direction of the thin plate to supply currents to the coils selectively. CONSTITUTION:A thin plate 1 is transferred to an arrow mark A at a constant speed. On both sides of the transfer passage of the thin plate 1, electromagnetic induction heating devices 2, 2 are respectively arranged in opposition to the thin plate 1. The devices 2, 2, are provided with magnetic pole segments 21, 21 arrayed mutually in parallel to the cross direction of the thin plate 1 and coils a1-a4, b1-b4 wound on the segments 21, 21 in parallel along the moving direction of the thin plate 1. The coils a1-a4 and b1-b4 are connected together in series, and the series connecting element of the coils a1-a4 and the series connecting element of the coils b1-b4 are connected together in series. Control by a feeding control means to supply currents to the coils a1-a4 and the coils b1-b4 selectively allows the heating speed of the thin plate 1 in a great measure.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electromagnetic induction heating device for heating a thin plate by electromagnetic induction.

[Prior Art] Conventionally, as this type of electromagnetic induction heating device, one is known that is arranged so as to face both sides of a thin plate that is fed at a constant speed in a predetermined direction.

This conventional electromagnetic induction heating device has magnetic pole segments arranged in parallel with each other in the width direction of the thin plate, multiple coils wound around the magnetic pole segments in parallel in the moving direction of the thin plate, and all of the multiple coils are constantly connected to each other. It was equipped with a power supply circuit that supplied current.

[Problems to be Solved by the Invention] For example, when annealing a rolled thin plate, it may be necessary to greatly change the heating rate of the thin plate depending on the type of the thin plate.

However, with conventional electromagnetic induction heating devices, when changing the heating rate of a thin plate, the only thing that can be done is to change the magnitude of the current supplied to the coil, so there is a problem that the heating rate of the thin plate cannot be changed very much. Ta.

An object of the present invention is to provide an electromagnetic induction heating device that can greatly change the heating rate of a thin plate.

[Means for Solving the Problems] According to the present invention, in an electromagnetic induction heating device that is arranged to face a thin plate that is fed at a constant speed in a predetermined direction, a plurality of coils wound around the magnetic pole segments in parallel along the moving direction of the thin plate; and a power supply control means for selectively supplying current to the plurality of coils. An electromagnetic induction heating device is obtained.

[Function] The present invention can change the heating rate of a thin plate by selectively supplying current to a plurality of coils of an electromagnetic induction heating device.

[Embodiments] Next, two embodiments of the present invention will be described in detail based on the drawings.

In FIGS. 1 and 2, reference numeral 1 indicates a thin plate such as a hot strip. This thin plate 1 is transported at a constant speed in the direction of arrow A by a transport mechanism (not shown).

Electromagnetic induction heating devices 2.2 are arranged on both sides of the movement path of the thin plate 1 so as to face the thin plate 1, respectively. The induction heating device 2.2 includes a plurality of magnetic pole segments 21.21 arranged in parallel with each other in the width direction of the thin plate 1, and a plurality of magnetic pole segments 21.21 wound around the magnetic pole segments 21.21 in parallel along the moving direction of the thin plate 1. A plurality of coils a1 to a4. t)+~
b4.

The plurality of coils a1 to a4 are connected to relays R1, R2)R3' normally closed contacts RIll+R, respectively, as shown in FIG.
211, R, connected in series through the power).

The plurality of coils b1 to b4 are connected in series.

A series connection body of these coils a1 to a4 and a coil b1
-b4 are connected in series.

The connection point between the coil a1 and the normally closed contact R1 of the relay R1 and the connection point between the coil b1 and the coil b2 are connected via the normally open contact R1m of the relay R1. A connection point between coil a2 and normally closed contact R2b of relay R2,
The connection point between coil b1 and coil b2 is connected via a normally open contact R2b of relay R2. The connection point between coil a and normally closed contact R3b of relay R5, and coil b,
The connection point between and coil b is the normally open contact R3 of relay R5.
Connected via M.

A secondary coil T2 of a transformer T and a variable capacitor C are connected in parallel between the coil a1 and the coil b1, and an AC power source 2 is connected to the primary coil T1 of the transformer T.
2 are connected.

Further, the relays R1, R2)Rs are each separately connected to the power supply control circuit 23. This power supply control circuit 23 is given information from a heating rate setting device 24 for the operator to set the heating rate. The power supply control circuit 23 is
Based on the information from the heating rate setting device 24, relay R1
, R2) R3 or %)
The power supply is controlled so that there is no deviation in power supply.

Now, when power is supplied to relay R1, the normally closed contact R1b opens and the normally open contact R0 closes.

An alternating current from an alternating current power supply 22 is supplied to the coil a1 and the coil b1 via the transformer T.

Moreover, when power is supplied to relay R2, normally closed contact R2b opens, and normally open contact R2a (closed).

Coil a1. AC power supply 2 to a2 and coil b+, 1)2
An alternating current from 2 is supplied via the transformer T.

Further, when relay R3 is energized, normally closed contact R3b opens and normally open contact R3m closes.

Coil a1+ 2+ a3 and coil bt, b2.
b, and an alternating current power from the alternating current power supply 22 (supplied via the transformer T).

On the other hand, when the relays R1, R2) and R3 are not supplied with power, the coils a1 to a4. AC current power from the AC power supply 22 (supplied via the transformer T) is applied to all of b+ to b4.

In the above, each adjacent coil a1 to a4
Currents of opposite polarity are passed through r bl-b4.

Now, when the magnitude and frequency of the alternating current from the AC power source 22 are the same, the moving speed of the thin plate 1 is V, and the moving speed of the thin plate 1 is
If the amount of heating is ΔT and the heating area is L, the heating rate HR of the thin plate 1 can be expressed approximately by the following equation.

HR-ΔT-V/L...(1
) Therefore, the moving speed V of the thin plate 1 and the AC power source 22
By changing the heating area if the magnitude and frequency of the alternating current from the source are the same.

The heating rate HR of the thin plate 1 can be varied.

Therefore, as shown in Fig. 3, the heating area when power is being supplied to the coils a, , b is Ll, and the heating area is Llat r.
Let L2 be the heating area when power is being supplied to 2 r bI r b2, and let be the heating area when power is being supplied to coils a1 to a3 + bl to b3.

The heating area when power is being supplied to the coils a1 to a4+bl to b4 is L4, and L4-4 L+.

When Li = 3Lt, L2 -2L+L-L, HR, -ΔT-V/L.

In the case of L-L2 shall be.

...(2) HR2-ΔT-V/L2- (ΔT-V/L,) ...(3) In the case of L-L3, HR3-ΔT-V/L 3- (ΔT-V/L,) ...(4) In the case of L "" La HR4-Δ"r-V/L4 -- (ΔT-V/L+
)...(5) becomes.

As is clear from these equations (2) to (5).

When L is set to be twice, three times, or four times as large as Ll, HR is shown in FIG. 4 as another embodiment of the present invention, which will be explained next.

Each of the plurality of coils al+a2 is connected to a relay R4.
, R6 are connected in series through normally closed contacts R4, and the plurality of coils b, , b2 are connected in series. A series connection body of these coils al+82 and coils b,...
The series connection body b2 is connected in series.

The connection point between coil a1 and normally closed contact R4 of relay R4 and the connection point between coil b1 and coil b2 are connected via normally open contact R4 of relay R4.

A secondary coil T-2 of a transformer T- and a variable capacitor C' are connected in parallel between the coil a1 and the coil b1, and the primary coil T- of the transformer T- is connected to an AC power supply. 25 are connected.

Further, the relays R4 and Rs are each separately connected to the power supply control circuit 26. This power supply control circuit 26 is given information from a heating rate setting device 27 through which the operator sets the heating rate.

Based on the information from the heating rate setting device 27, the power supply control circuit 26 controls the power supply so as to supply power to either relay R4, R, or not to supply power to any of them.

Now, when power is supplied to relay R4, the normally closed contact R4° opens and the normally open contact R4 closes.

An alternating current from an alternating current power supply 22 is supplied to the coils a and b1 via a transformer T.

Further, when power is supplied to relay R5, normally closed contact R9 opens and normally open contact R5 closes.

An alternating current from an alternating current power supply 25 is supplied to the coil a3+ and the coil b via the transformer T'.

On the other hand, if power is not supplied to relay R4.

An alternating current from an alternating current power supply 22 is supplied to the coil a+ + &2+ br r b2 via a transformer T.

Also, if power is not supplied to relay R5.

An alternating current from an alternating current power supply 25 is supplied to the coil as+a4+b3+b4 via a transformer T'.

ON/OFF of the AC power supply 22.25 and relay R
4. AC power supply 2 from R9 ON/OFF combination 1
2.25 can selectively supply current to the coils a1-b, -b4.

Note that the electromagnetic induction heating device has n (n≧2) pairs (Ile a,
, b, the current is selectively supplied to the coil by 2 to n 1's.

By configuring the coil to be selectively supplied with electricity by a plurality of power supplies in this way, the power supplied to the coil can be greatly changed, and the power supplied by each power supply can also be reduced.

[Effects of the Invention] According to the present invention, the heating rate of the thin plate can be increased.

Fig. 1 is a perspective view showing one embodiment of the present invention, Fig. 9 is a sectional view showing a part of the same embodiment, and Fig. 3 1t shows a circuit for feeding power to the coil of the above embodiment. FIG. 4 is an electric circuit diagram showing a circuit for feeding power to a coil in another embodiment of the present invention.

1... Thin plate, 2... Electromagnetic induction heating device, a1 to a4
+b1 to b4... Coil, 22.25... AC power supply, 23.26... Power supply control circuit, 24.27... Heating rate setting device.

transformation child

Claims (2)

[Claims] (1) In an electromagnetic induction heating device arranged to face a thin plate that is fed at a constant speed in a predetermined direction, a plurality of magnetic pole segments arranged in parallel with each other in the width direction of the thin plate, and the magnetic poles 1. An electromagnetic induction heating device comprising: a plurality of coils wound around a segment in parallel along the moving direction of a thin plate; and a power supply control means for selectively supplying current to the plurality of coils. (2) The electromagnetic induction heating device according to claim 1, wherein the power supply control means selectively supplies current to the plurality of coils from a plurality of power supplies.