JP2935087B2 - Induction heating device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an induction heating apparatus, and more particularly to an induction heating apparatus for continuously heating a strip (thin plate) fed in a predetermined flow direction by electromagnetic induction.

[0002]

2. Description of the Related Art As this type of induction heating apparatus, there is an apparatus for heating a strip having a length longer than a width by using electromagnetic induction. Such an induction heating device comprises an electromagnet arranged on one or both sides of the strip so as to face the strip in the width direction of the strip, and the electromagnet is energized by an alternating current. In this induction heating device, it is desirable that the heating can be performed uniformly in the width direction of the strip. This type of induction heating apparatus generates magnetic lines of magnetic force (magnetic flux) in the traveling direction of the strip to heat the strip (hereinafter referred to as an LFX type induction heating apparatus), and generates magnetic lines of force in the vertical direction of the strip. Heating device for heating the strip by heating (hereinafter referred to as VFX type induction heating device)
And two.

Conventionally, there have been proposed various VFX induction heating apparatuses for uniformly heating the temperature distribution in the strip width direction of a strip.

Japanese Patent Publication No. 63-27836 (hereinafter referred to as Prior Art 1) discloses a plurality of magnetic pole segments arranged in parallel with each other and in opposition to a strip in a strip width direction. A drive mechanism for moving the magnetic pole segment in the thickness direction of the strip independently of the other magnetic pole segments, a coil common to the plural magnetic pole segments arranged so as to surround the plural magnetic pole segments, and a strip. An "electromagnetic induction heating device" is disclosed which includes a non-magnetic metal magnetic shielding material that is provided so as to be able to protrude and retract in the width direction and adjusts a magnetic field from a magnetic pole segment.

Next, with reference to FIG. 7, a description will be given of a conventional VFX type induction heating apparatus disclosed in the prior art 1. The illustrated VFX induction heating apparatus includes a main coil 1 for generating a magnetic flux, a high-frequency power supply (not shown) for flowing a high-frequency current through the main coil 1, and a main iron core around which the main coil 1 is wound. 2 and a magnetic shielding material (F / M) 10 for adjusting the magnetic flux density at the edge of the strip (material to be processed) 9. A combination of the main coil 1 and the main iron core 2 forms a main inductor. The main iron core 2 is composed of a pair arranged opposite to each other with the strip 9 interposed therebetween. The main iron core 2 is for increasing the magnetic flux density generated by the main coil 1, suppressing the leakage magnetic flux, and increasing the heating efficiency of the strip 9.

The strip 9 is supplied to the VFX type induction heating apparatus while continuously moving, for example, from above to below in FIG. In a thin plate-shaped conductive strip 9,
When an alternating magnetic flux having a vertical directional component is applied, an induced current (eddy current) is generated in the strip 9 so as to cancel it, and the strip 9 generates heat by the Joule heat. Utilizing this phenomenon, the VFX induction heating device heats the strip 9. The temperature distribution (outlet temperature distribution) in the width direction (plate width direction) of the strip 9 after passing through the VFX type induction heating device is based on the Joule heat distribution due to the eddy current generated on the plane of the strip 9 inside the device. It is integrated in the traveling direction of the strip 9 (plate length direction).

The generated eddy current has a property of being concentrated at the edge portion (plate edge portion) of the strip 9 according to the boundary condition of the electromagnetic field. Therefore, the outlet side temperature distribution is such that the plate edge is heated.

In the prior art 1, the main iron core 2 is divided into several magnetic pole segments in the width direction of the plate to suppress a rise in the temperature of the plate edge portion and obtain a uniform outlet temperature distribution. The pole segments are individually movable in the vertical direction of the strip 9 by a drive mechanism (not shown). Thereby, the distance (iron core gap) between the main iron cores 2 facing each other across the strip 9 can be individually changed, and the magnetic flux density applied to the strip 9 can be adjusted in the width direction. Thereby, the outlet temperature distribution is adjusted.

Further, the magnetic shielding material 10 is made of a substance having a small electric resistivity (for example, copper). By generating an eddy current inside the magnetic shielding material 10, the magnetic shielding material 10 is sandwiched between the opposing magnetic shielding materials 10. In the space, the magnetic flux generated by the main coil 1 and the main iron core 2 is shielded, and the magnetic flux density in the space is attenuated. The magnetic shielding material 10 is movable in the plate width direction, and the overlapping length (F / M insertion amount) of the strip 9 and the magnetic shielding material 10 can be changed. Thereby, the applied magnetic flux density at the plate edge portion can be adjusted to be small when the F / M insertion amount is large and to be large when the F / M insertion amount is small.
Therefore, it is possible to adjust the temperature of the outlet side temperature distribution, particularly the temperature at the plate edge portion.

Japanese Patent Laid-Open Publication No. Hei 1-204385 (hereinafter referred to as Prior Art 2) discloses a first inductor (main inductor) having an iron core longer than a plate (strip) width having one slot. An "induction heating device" including a second inductor (auxiliary inductor) that is provided to be movable in the plate width direction and that heats both ends of the plate material is disclosed.

Japanese Patent Application Laid-Open No. 63-190281 (hereinafter referred to as
The prior art 3) includes a main coil portion (main inductor).
In an induction heating device comprising an auxiliary coil portion (auxiliary inductor) extending in the longitudinal direction of a flat plate (strip), the auxiliary coil portion is inclined in accordance with the insufficient temperature in a portion of the main coil portion where the temperature rise is insufficient. A "method and apparatus for induction heating a flat plate" which is adjusted is disclosed.

Japanese Patent Application Laid-Open No. 63-119187 (hereinafter referred to as
In the prior art 4), the temperature distribution is reduced by arranging a plurality of inductors whose heat generation distribution is reduced symmetrically with respect to a predetermined peak point in the flow direction of the material to be heated (strip). A "method of induction heating of a steel sheet using a transverse magnetic flux" which can be uniform is disclosed.

Japanese Patent Publication No. 4-49233 (hereinafter referred to as Prior Art 5) discloses a first inductor (main inductor) in which a current distribution is diffused at an edge portion of a strip-shaped metal (strip); The second type that concentrates on the department
Combination with the inductor (auxiliary inductor)
Discloses a "band-shaped metal induction heating device using a transverse magnetic flux" in which the rotational position of the inductor is adjusted and the degree of diffusion of the edge current density in the first inductor can be changed.

[0014]

The conventional V shown in FIG.
In the FX-type induction heating apparatus, when the F / M insertion amount is adjusted so that the plate edge portion temperature of the outlet side temperature distribution becomes equal to the temperature near the center of the strip 9 (the plate center), the inside of the plate edge portion is slightly adjusted. A low temperature region (hereinafter, referred to as a low temperature region) occurs. Further, the temperature decrease amount and the region width in the low temperature region change depending on the thickness of the strip 9, the electrical resistivity, and the like.

The temperature in the low-temperature region can be increased by reducing the iron core gap at a position corresponding to the low-temperature region. However, if the iron core gap is too narrow, the strip 9 comes into contact with the main iron core 2 due to plate warpage or vibration,
There is a possibility that the strip 9 may be damaged.

Further, the low-temperature region is close to the plate edge, and the iron core gap is reduced to increase the magnetic flux density at the plate edge, thereby increasing the temperature of the plate edge adjusted by the magnetic shielding material 10. For this reason, it has not been possible to adjust the temperature of both the plate edge and the area slightly inside the plate edge.

The eddy current generated in the conventional VFX type induction heating apparatus shown in FIG.
Circulate as shown. The eddy current flowing in the plate width direction near the plate center a changes its direction in the plate longitudinal direction at a position b slightly inside the plate edge. At this position b, the density of the eddy current becomes low. As described above, the outlet temperature distribution is obtained by integrating the Joule heat distribution generated by the eddy current in the plate longitudinal direction. Therefore, a low-temperature region b of the temperature distribution is generated between the vicinity a of the plate center where the component of the eddy current in the width direction of the plate contributes to the heating and the plate edge c where the component of the eddy current in the plate longitudinal direction contributes to the heating. . FIG. 8B shows a heating pattern of the strip 9. In FIG. 8B, the vertical axis represents the temperature rise value,
The horizontal axis indicates the position of the strip 9 in the width direction.

As described above, in order to obtain a uniform outlet temperature distribution with high accuracy, in the conventional VFX type induction heating apparatus shown in FIG. 7, the vortex between the plate edge portion and a region slightly inside thereof is formed. The current distribution cannot be adjusted sufficiently.

Accordingly, an object of the present invention is to provide an induction heating apparatus capable of controlling an eddy current distribution generated in a region slightly inside both ends of a strip and performing extremely uniform heating in the width direction of the strip. Is to do.

Incidentally, the "induction heating device" disclosed in the prior art 2 only compensates for the insufficient heating at both ends of the strip by the first inductor by the second inductor, as in the present invention. , Different from temperature compensation of the temperature drop at a point slightly inside the ends of the strip.

The "induction heating method and apparatus of a flat plate" disclosed in the prior art 3 is such that an auxiliary coil portion extending in the length direction of a flat plate (strip) is provided with respect to a main coil portion in a running direction of the flat plate. It is installed on the upstream side, downstream side, or inclined between the main coil parts. Since the auxiliary coil portion extends in the length direction of the flat plate, the flat plate may be overheated. Further, since the auxiliary coil portion is disposed only on one side or between the main coil portions, the temperature of the flat plate cannot be adjusted with high accuracy.

The "induction heating method of a steel sheet using a transverse magnetic flux" disclosed in the prior art 4 is composed of a plurality of steel sheets whose heat generation distribution is reduced symmetrically about a predetermined peak point in the flow direction of the material to be heated. This is different from a method in which the inductor is disposed over the width of the plate and which compensates for a temperature drop portion slightly inside the both ends of the strip as in the present invention.

The “induction heating apparatus for a strip-shaped metal using a transverse magnetic flux” disclosed in the prior art 5 includes a first inductor in which a current distribution is diffused at an edge of the strip-shaped metal,
Only the combination with the second inductor of the type in which the current distribution is concentrated at the edge portion is disclosed, and what compensates for the temperature drop portion slightly inside the both ends of the strip as in the present invention is as follows. different.

[0024]

An induction heating apparatus according to the present invention is an induction heating apparatus for heating a strip fed in a predetermined flow direction by electromagnetic induction, wherein a main inductor is interposed in the strip flow direction. Auxiliary inductors are arranged in parallel on both sides of the strip, and the auxiliary inductors are provided separately at both edges of the strip and form a pair of N and S poles in the width direction of the strip. A coil is connected to the main inductor and the auxiliary inductor such that the magnetic pole at the end of the main inductor and the magnetic pole on the strip edge side of the auxiliary inductor adjacent to the magnetic pole have opposite polarities. And each of the auxiliary inductors heats the strip in a spot shape.

[0025]

The auxiliary inductor simultaneously suppresses a rise in the temperature of the plate edge and a decrease in the temperature of the region slightly inside. Since the strip is heated in a spot shape by the auxiliary inductor, overheating of the strip can be suppressed.

[0026]

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows the structure of a VFX type induction heating apparatus according to one embodiment of the present invention. FIG. 2 shows a state in which the strip and its front-side elements have been removed for easy understanding. 1 and 2, the same elements are denoted by the same reference numerals.

The illustrated VFX-type induction heating apparatus includes an auxiliary inductor composed of auxiliary coils 31 and 32 and an auxiliary iron core 4 in addition to a main inductor composed of a main coil 1 and a main iron core 2. A total of eight strips are installed on the top, bottom, left, right, front and back of the strip 9. In FIGS. 1 and 2, among the two magnetic poles of the auxiliary iron core 4, the auxiliary coil installed inside the strip 9 in the plate width direction is denoted by reference numeral 31, and the auxiliary coil also installed outside Reference numeral 32 is attached. Therefore, in the following, the auxiliary coil 3
1 and 32 will be referred to as an inner auxiliary coil and an outer auxiliary coil, respectively.

As shown in FIGS. 1 and 2, the main iron core 2 is divided into several magnetic pole segments in the plate width direction, and the VFX type induction heating device separates the magnetic pole segments into strips 9 individually. It has a mechanism (not shown) that can move in the vertical direction. The VFX-type induction heating device has a mechanism (not shown) capable of individually moving eight sets of auxiliary inductors in the plate width direction. The VFX type induction heating device has a mechanism (not shown) capable of moving the auxiliary iron core 4 in a direction perpendicular to the strip 9. Since the auxiliary coils 31 and 32 are movable in the plate width direction, they are connected in series with the main coil 1 by a mechanically flexible conductor (for example, a cable) 5 and are coupled to the high-frequency power supply 6.

In the present invention, the direction of the current supplied to each coil is important, and the direction of the current supplied to the main coil 1 at a certain moment is, for example, clockwise or counterclockwise along the plate longitudinal direction. It must be alternately inverted, such as around. On the other hand, at the same moment, the inner auxiliary coil 31
Is the same as the rotation direction of the main coil 1 closest to the same coil, and the current supplied to the outer auxiliary coil 32 must be opposite to the direction of the inner auxiliary coil 31.

The coils facing each other across the strip 9
It must be wound around the iron core so that the direction of the current flowing therethrough is mirror-like with the strip 9 as the plane of symmetry. In order to easily understand the winding direction of the coil, for convenience, the names of the magnetic poles at certain moments are denoted by “N” and “S” in FIGS. It is added to the core 4.

As described above, since the high-frequency current supplied to each coil needs to have the same phase, in this embodiment, each coil is connected in series and supplied from the same high-frequency power supply 6. ing. Instead, the power may be supplied to each coil by using a separate high-frequency power supply device whose phases are controlled to be synchronized.

The strip 9 is continuously supplied to the VFX type induction heating apparatus while moving, for example, from top to bottom in FIG.

In the first embodiment, the number of the main coils 1 and the number of magnetic poles of the iron core 2 are two for each of the front and back surfaces of the strip 9, but the number may be any number. Further, in the first embodiment, the auxiliary iron core 4 has a U-shape as shown in FIG.
The curved surface portion may be set as shown in FIG. Further, the first
Although the embodiment has been described with the magnetic shielding material (F / M) 20 removed to avoid complicating the description, the F / M conventionally used may be provided.

Next, referring to FIG. 1 and FIG.
The operation of this embodiment will be described. When each of the eight sets of auxiliary inductors is adjusted to an appropriate position by a plate width direction moving mechanism (not shown), an eddy current as shown in FIG.

At the position a in FIG. 4, the eddy current, which has been concentrated on the plate edge due to the magnetic pole formed by the main coil 1 in the related art, is partially inside the plate edge by the magnetic pole formed by the auxiliary coil 32. Is pushed away. Thereby, the temperature rise of the plate edge can be suppressed.

Further, due to the magnetic poles formed by the inner auxiliary coil 31 and the outer auxiliary coil 32, a location where the eddy current is concentrated in the longitudinal direction of the plate is newly generated at a position b in FIG. The amount of heat generated by the eddy current in the portion b coincides with the region in which the temperature has been reduced in the conventional direction in the plate width direction, and operates so as to compensate for it.

Further, the moving mechanism of the auxiliary iron core 4 is used in FIG.
The calorific value and the width of the heat generating region of the b portion in the middle can be adjusted at the same time, and it is possible to cope with the heating of various strips 9 having different physical specifications such as plate thickness and electric resistivity.

As described above, the auxiliary inductor composed of the inner auxiliary coil 31, the outer auxiliary coil 32 and the auxiliary iron core 4 according to the present invention prevents the temperature rise at the plate edge portion and the temperature decrease at the slightly inner region. At the same time, they can be suppressed, and a uniform outlet temperature distribution can be obtained with high accuracy as shown in FIG.

Referring to FIG. 5, movement of auxiliary inductor /
The rotation mechanism 11 will be described. As shown by an arrow A in FIG. 5B, the auxiliary inductor is connected to the moving / rotating mechanism 11.
Is moved in the width direction of the strip 9. FIG.
As shown in (c), the auxiliary inductor has a structure rotatable by the movement / rotation mechanism 11. here,
As the movement / rotation mechanism 11, for example, a combination of a movement mechanism 11A including a screw feed mechanism and a slide mechanism and a rotation mechanism 11B including a worm and a worm wheel can be used.

With such a configuration, the eddy current flowing through the strip 9 flows as shown in FIG. 6A, and the portion where the current density is high is at the position shown by the oblique lines in FIG. 6A. Further, this position can be freely adjusted by the movement / rotation mechanism 11 shown in FIG. FIG. 6B shows a temperature distribution due to the heating of the strip 9 by the auxiliary inductor. Accordingly, the temperature distribution caused by heating the strip 9 by only the main inductor (FIG. 8B) and the temperature distribution caused by heating of the strip 9 by only the auxiliary inductor (FIG. 6)
By the combination with (b)), the temperature distribution of the strip 9 can be made uniform.

Although the present invention has been described with reference to preferred embodiments, the present invention is not limited thereto, and various modifications and changes can be made without departing from the spirit of the present invention.
For example, in the above embodiment, both the main and auxiliary inductors are arranged opposite to both sides of the strip, but both the main and auxiliary inductors may be arranged only on one side of the strip. Further, the auxiliary inductor may be provided so as to be adjustable in position in the longitudinal direction of the strip with respect to the main inductor.

[0043]

As described above, according to the present invention, a uniform outlet temperature distribution can be obtained by adjusting the eddy current distribution in the plate edge portion and a region slightly inside the edge portion. According to the present invention, rapid heating of the strip is possible without impairing the feature of the conventional VFX-type induction heating device in which the heating area is short in the plate longitudinal direction. Since a uniform outlet-side temperature distribution can be obtained in the short plate length direction heating region, the distortion of the strip due to heating can be minimized. Further, since the temperature adjusting action of the plate edge portion, which was conventionally performed by the magnetic shielding material (F / M), is realized by the auxiliary inductor in the present invention.
Conventionally, the heat generated by the F / M itself that has not contributed to heating the strip due to the eddy current generated inside the F / M, that is,
Useless power consumption is eliminated, and high heating efficiency is obtained.
Further, even when the F / M is installed, the F / M is set outside the strip so as to generate heat in the induction heating device structure and the like, and to perform a function of shielding a leakage magnetic flux that does not contribute to heating the strip. Therefore, a higher heating efficiency can be obtained as compared with the related art. Since the auxiliary inductor according to the present invention heats the strip in a spot shape, for example, as compared with the case where the auxiliary inductor extends in the length direction of the strip as in Prior Art 3, overheating of the strip is prevented. Can be suppressed.

[Brief description of the drawings]

FIG. 1 is a perspective view illustrating a configuration of an induction heating device according to an embodiment of the present invention.

FIG. 2 is a perspective view showing a state in which a strip and elements on a front side thereof are removed from the induction heating apparatus shown in FIG. 1;

FIG. 3 is a perspective view showing a modification of the auxiliary inductor used in the induction heating device according to the present invention.

FIG. 4 is a diagram showing an eddy current and a temperature distribution generated in a strip in the induction heating device shown in FIG.

FIG. 5 is a view showing a movement / rotation mechanism of an auxiliary inductor used in the induction heating device according to the present invention.

6 is a diagram showing an eddy current and a temperature distribution generated in a strip by only the auxiliary inductor shown in FIG. 5;

FIG. 7 is a perspective view showing a configuration of a conventional induction heating device.

8 is a diagram showing an eddy current and a temperature distribution generated in a strip in the induction heating device shown in FIG. 7;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Main coil 2 Main iron core 31, 32 Auxiliary coil 4 Auxiliary iron core 5 Conductor which couples an auxiliary coil 6 High frequency power supply 9 Strip (material to be processed) 11 Moving / rotating mechanism

Claims (1)

(57) [Claims] In an induction heating apparatus for heating a strip fed in a predetermined flow direction by electromagnetic induction, auxiliary inductors are arranged side by side with a main inductor interposed therebetween in the strip flow direction. Auxiliary inductors are provided separately at both edges of the strip, and include an N pole and an S pole in the width direction of the strip.
The main inductor and the main inductor so that the magnetic pole at the end of the main inductor and the magnetic pole on the strip edge side of the auxiliary inductor adjacent to the magnetic pole have opposite polarities. An induction heating device, wherein a coil is connected to an auxiliary inductor, and each of the auxiliary inductors heats the strip in a spot shape.