JPH0690949B2 - Electromagnetic induction heating device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an electromagnetic induction heating device, and more particularly to an electromagnetic induction heating device for continuously heating a thin plate or the like.

(Prior Art) Generally, in this type of electromagnetic induction heating device, there is one that heats a thin plate (strip) having a length longer than its width by using electromagnetic induction.

Conventionally, as an electromagnetic induction heating device for strips, an electromagnetic induction heating device (hereinafter referred to as LFX heating device) that heats a steel plate by generating magnetic field lines in the traveling direction of the strip.
And an electromagnetic induction heating device (hereinafter referred to as VFX heating device) that heats a steel sheet by generating magnetic field lines perpendicular to the traveling direction of the steel sheet.

(Problems to be solved by the invention) By the way, in the case of the LFX heating device, it is extremely difficult to heat the steel plate if the thickness of the steel plate is 0.4 mm or less. On the other hand, in the VFX heating device, the energization amount is increased to reduce the magnetic flux. In many cases, there is a problem that the steel plate is adsorbed on the yoke of the electromagnet.

An object of the present invention is to provide an electromagnetic induction heating device in a VFX heating device in which a steel sheet is not attracted to an electromagnet even if the amount of electricity supplied is increased.

(Means for Solving Problems) The present invention relates to an electromagnetic induction heating device for continuously heating a steel sheet sent in a predetermined direction by electromagnetic induction,
A first electromagnet including a first yoke and a plurality of magnetic poles arranged on one surface of the first yoke in the plate width direction of the steel sheet at predetermined intervals, and facing the first yoke. And a second electromagnet having a plurality of magnetic poles arranged on one surface of the second yoke and facing the magnetic poles of the first electromagnet. The magnetic poles of the first electromagnet and the second electromagnet, which are opposed to each other, are magnetized with their phases shifted by 90 degrees.

(Operation) The magnetic poles of the first electromagnet and the second electromagnet that face each other are
Since the magnets are magnetized with a 90-degree phase shift, electromagnetic attraction acts alternately on the steel sheet. Therefore, the steel plate will not be attracted to the electromagnet.

(Example) Hereinafter, the present invention will be described with reference to examples.

First, an outline of the VFX heating device will be described with reference to FIG.

A plurality of magnetic pole pieces 2a, 2b, 2c extending in the traveling direction of a steel plate (not shown) on one end surface (lower end surface) of the yoke 1 at a predetermined interval.
And 2d are set. Coils 3a, 3b, 3c, and 3d are wound around the pole pieces 2a, 2b, 2c, and 2d, respectively.
The electromagnet 4 is configured by forming 2, 33, and 34. On the other hand, the yoke 5 is arranged so as to face the yoke 1,
Of the magnetic pole pieces 6a, 6b, 6c, and 6d are formed on one end surface (upper surface) of the magnetic pole pieces 6a, 6b, 6c, and 6d so as to face the magnetic pole pieces 2a, 2b, 2c, and 2d.
Coils 7a, 7b, 7c, and 7d are wound around c and 6d, respectively, and magnetic poles 71, 72, 73, and 74 are formed, and an electromagnet 8 is configured.

A steel plate (not shown) is sent through a passage (gap) formed between the electromagnets 4 and 8. At this time,
As will be described later, the coils 3a to 3d and the coils 7a to 7d are energized, the magnetic poles 31 to 34, 71 to 74 are magnetized to generate magnetic force lines,
The steel sheet is heated by electromagnetic induction.

Here, the energization control of the conventional electromagnetic induction heating device will be described with reference to FIG.

A single-phase AC voltage is applied to the coils 3a to 3d and 7a to 7d.
By energizing the coils 3a to 3d, for example, the magnetic poles 31 to 34 become S-pole, N-pole, S-pole, and N-pole from the left side, while the coil 7a
By energizing ~ 7d, the magnetic poles 71-74 are N pole, S sequentially from the left side.
It becomes a pole, N pole, and S pole. In this way, energization is controlled so that the opposing magnetic poles of the electromagnets 4 and 8 are different magnetic poles. Then, magnetic force lines are formed as shown by the one-dot chain line in FIG.

By the way, as shown in FIG. 5, when a magnetic pole (N pole, S pole) is formed by a single-phase alternating current, the attraction force by the electromagnets 4 and 8 is always equal, and the attraction force by the electromagnets 4 and 8 has a magnetic path length. Since it acts on the steel sheet so as to shorten it, unless the steel sheet is inserted parallel to the electromagnets 4 and 8 and in the center of the passage, the steel sheet will be moved in a direction perpendicular to the traveling direction. This state is shown in FIGS. 6 (a), (b), and (c).
Shown in. That is, as shown in FIG. 6 (a), a steel plate is attracted to one electromagnet (for example, electromagnet 4), or as shown in FIG. 6 (b), one side end is attracted toward the magnet 4. On the other hand, the other end is attracted toward the electromagnet 8 and the strip is twisted. Furthermore, as shown in FIG. 6 (c), both ends of the steel plate are attracted toward the electromagnet 4,
In some cases, normal electromagnetic induction heating may not be possible because the steel plate is warped.

Next, the electromagnetic induction heating device according to the present invention will be described. The structure of the electromagnetic induction heating device itself is the same as in FIG.

Referring to FIG. 3, an AC power supply 9 is connected to one end of a coil 7d via a capacitor 10, and the coil 7d is a coil in sequence.
7c, the coil 3b, and the coil 3a, and the coil 3a is connected to the AC power supply 9. Further, the AC power supply 9 is a coil
The coil 11 is connected to the coil 3d, the coils 3c and 7b, and the coil 7a sequentially, and the coil 7a is connected to the AC power supply 9. A capacitor 12 is connected to one end of the coil 7a and the other end of the coil 3d, while a capacitor 13 is connected to one end of the coil 3a and one end of the coil 7d. coil
11 and the capacitor 10 are selected to have predetermined (appropriate) values, and the current flowing through the coils 3a, 3b, 7c, 7d (path I) and the coils 7a, 7
The phase should be 90 degrees out of phase with the current flowing through b, 3c, 7d (path II).

Here, referring to FIG. 1, as currents whose phases are shifted by 90 degrees, _A = K _sin θ, (K is a coefficient (amplitude) θ is 2πft. F is frequency and t is time). And in this case, the current _B is
And the current _A flows through the path I.

As shown in FIG. 1 (a), when θ = O, the magnetic poles 71, 72,
33 and 34 are magnetized to N pole, S pole, S pole, and N pole, respectively, and magnetic force lines are generated as shown by solid arrows. When θ increases, the magnetic flux of the magnetic poles 71, 72, 33, and 34 gradually decreases, while the magnetic poles 31, 32, 73, and 74 are magnetized, and the N pole, respectively.
The magnetic flux gradually increases as it becomes S pole, S pole, and N pole. θ
= 45 °, the magnetic fluxes of the magnetic poles 31 to 34 and 71 to 74 become equal, and in this case, magnetic force lines are generated as shown by solid arrows in FIG. As shown in FIGS. 1 (c), (d), (e), (f), (g), and (h), the magnetic poles N and S change as θ increases. Magnetic lines of force are formed as indicated by solid arrows. And θ = 36
At 0 °, the state returns to that shown in FIG.

Here, the currents _A and _B are θ = 0 ° (θ = 180 °) and θ = 9
It corresponds to FIG. 1 (a) (FIG. 1 (e)) and FIG. 1 (c) (FIG. 1 (g)) showing the formation of magnetic force lines at the position of 0 ° (θ = 270 °), respectively. 2 (a) and (b)
Referring to FIG. 1, in the state shown in FIG.
When θ passes through the electromagnetic induction heating device, in the state of θ = 0 °, as shown in FIG. 2 (a), a part of the magnetic force lines from the magnetic pole 72 (N pole) passes through the steel plate 14 and the magnetic pole 71 Reach (S pole). As a result, the left side portion of the steel plate 14 is pulled in the direction of the magnetic poles 71 and 72, that is, in the direction indicated by the thick arrow. On the other hand, similarly, the right side portion of the steel plate 14 is drawn in the direction of the magnetic poles 33 and 34, that is, in the direction indicated by the thick line arrow. In the state of θ = 90 °, as shown in FIG. 2 (b), a part of the magnetic force lines from the magnetic pole 31 (N pole) passes through the steel plate 14 and reaches the magnetic pole 32 (S pole). As a result, the left side portion of the steel plate 14 is pulled in the direction of the magnetic poles 31 and 32, that is, in the direction indicated by the thick line arrow. On the other hand, similarly, the right side portion of the steel plate 14 is in the direction of the magnetic poles 73 and 74,
That is, it is drawn in the direction indicated by the thick arrow.

As is clear from the above description, since alternating currents 90 degrees out of phase are applied to the coils of the opposite magnetic poles of the electromagnets 4 and 8, that is, the opposite magnetic poles of the electromagnets 4 and 8 are 90 degrees.
Since the magnets are magnetized out of phase with each other, the N pole and the S pole are sequentially formed as shown in FIGS.
Moreover, since the magnetic flux amounts of the magnetic poles are the same instantaneously, the attractive force acts substantially alternately on the steel sheet, and as a result, the attraction of the steel sheet to the magnetic poles can be prevented.

(Effects of the Invention) As described above, in the electromagnetic induction heating apparatus according to the present invention, since the two-phase alternating current with a 90-degree phase shift is used, the attractive force acts alternately on the steel plates, and the steel plates are attracted to the magnetic poles. Can be prevented. In other words, the steel plate is not attracted to the electromagnet even if the amount of electricity is increased.

[Brief description of drawings]

1 (a) to 1 (h) are diagrams showing magnetic lines of force formed by the electromagnetic induction heating apparatus according to the present invention, FIG. 1 (i) are diagrams showing two-phase alternating current, and FIGS. 2 (a) and 2 (b). ) Are views showing the suction force acting on the steel plate in the electromagnetic induction heating apparatus according to the present invention, FIG. 3 is a view showing a power supply circuit used in the electromagnetic induction heating apparatus according to the present invention, and FIG. 4 is an electromagnetic induction heating apparatus. FIG. 5 is a schematic diagram, FIG. 5 is a diagram for explaining energization control of a conventional electromagnetic induction heating device, FIG. 6 (a) is a diagram for explaining adsorption of a steel plate, and FIG. 6 (b) And (c)
FIG. 5 is a diagram showing FIG. 5 from the direction of the solid line arrow, and is a diagram showing adsorption of steel sheets, respectively. 1,5 …… Yoke iron, 4,8 …… Electromagnet, 9 …… AC power supply.

Claims (1)

[Claims] 1. An electromagnetic induction heating device for continuously heating a thin plate fed in a predetermined direction by electromagnetic induction, comprising: a first yoke and a plate of the thin plate on one surface of the first yoke. A first electromagnet having a plurality of magnetic poles arranged at predetermined intervals in the width direction, a second yoke arranged to face the first yoke, and a second yoke A second electromagnet having on one surface thereof a plurality of magnetic poles arranged to face the magnetic poles of the first electromagnet, and the first electromagnet and the second electromagnet.
The electromagnetic induction heating device is characterized in that the magnetic poles facing each other with the electromagnet are magnetized by shifting their phases by 90 degrees.