JPS6398993A - Induction heater - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an induction heating device for inductively heating a flat metal sheet conveyed by a metallic conveyance roll using a transverse magnetic flux heating method.

[Conventional technology 1 FIG. 5 shows a conventional transverse magnetic flux type induction heating device.

1 is a flat metal plate that is heated by induction, and is moved in parallel on a guide roll 2. Reference numeral 3 denotes a pair of transverse magnetic flux type heating induction coils that are provided on the upper and lower surfaces of the metal plate 1 so as to face each other, and the coil surface S of the coil 3 is parallel to the metal plate 1. In addition, the metal plate 1 is held through a predetermined gap G so as to be able to cope with changes in the thickness of the metal plate 1, etc.

Due to its structure, this transverse magnetic flux induction heating device is suitable for heating a wide metal plate, and requires less applied power than a cylindrical induction heating coil, which requires a higher frequency power source depending on the thickness of the plate. It has the advantage that the frequency is relatively low and approximately constant.

[Problems to be Solved by the Invention] However, in the heating device as described above, since there is a gap G between the heating coil 3 and the metal plate 1, magnetic flux leaks to the outside through this gap G. It becomes like this. FIG. 6 shows the distribution of leakage magnetic flux obtained through actual analysis. Incidentally, since the distribution of magnetic flux is symmetrical with respect to the traveling direction of the metal plate 1, only one side is shown in FIG. Leakage magnetic flux F
By interlinking with the metal plate 1 and the roll 2, an induced voltage is generated inside, and a current flows between the metal plate 1 and the roll 2 due to the difference in the induced voltage, and a spark is generated. Due to the generation of this spark, spark marks are created on the surfaces of both the metal plate 1 and the roll 2. Since the spark marks on roll 2 further promote the generation of the next spark, conventionally, this type of transverse magnetic flux induction heating device has been used in cases where the spark marks can be eliminated through subsequent processing, and in other cases where the spark marks are generated. It was only used when an insulated roll could be used for the roll 2 to avoid this problem.

Means for Solving Problem F 1 The induction heating device of the present invention is a transverse magnetic flux type induction heating device in which induction heating films are arranged on the upper and lower surfaces of a metal plate to be heated, and the induction heating device covers the outer surface of the induction heating coil. A feature is that a non-magnetic conductive member is provided to suppress leakage of magnetic flux to the outside.

[Function] According to the above configuration, by providing the non-magnetic conductive member as a magnetic shield on the outer surface of the induction heating coil,
Of the magnetic field emitted from the induction heating coil, leakage magnetic flux flowing out to the outside is shielded, and the above-mentioned adverse effects caused by leakage magnetic flux are eliminated.

[Example j ttS1 Figure shows one of the transverse magnetic flux induction type devices according to the present invention.
An example is shown. Note that the same parts as in the conventional example shown in FIG. 5 are given the same reference numerals.

In this embodiment, a box-shaped magnetic shield 4 is provided that covers the coil 3 except for the coil end surface S of the induction heating filter 3. A copper plate, which is a non-magnetic metal, is used for the magnetic shield 4, and by setting the plate thickness t to be equal to or greater than the penetration depth δ of the current applied to the induction heating coil 3, a good shielding effect can be obtained.

FIG. 2 shows the magnetic flux distribution in this case. As is clear from the figure, the leakage magnetic flux to the outside due to the induction heating filter 3 is significantly reduced by using the magnetic shield 4. As a result, the number of linkages of leakage magnetic flux to the metal plate 1 and the roll 2 is significantly reduced, and arcs are no longer generated due to the induced voltage between the metal plate 1 and the roll 2 as in conventional heating devices. The generation of spark marks can be suppressed. Moreover, the operating power factor of the induction heating filter 3 is improved due to the reduction in leakage magnetic flux, and the overall electrical efficiency is improved by about 3%.

FIG. 3 shows another embodiment of the invention.

At each end 4a of the magnetic shield 4, a leakage magnetic flux suppressing plate X is provided which is parallel to the metal plate 1 and further extends outward by a length. Similar to the magnetic shield 4, this leakage magnetic flux suppression plate
The thickness is about the same as that of the magnetic shield 4. FIG. 4 shows the distribution of leakage magnetic flux when such a leakage magnetic flux suppression plate X is used. As can be seen from the figure, by using this leakage magnetic flux suppression plate X, no magnetic flux leaks to the outside, and the magnetic sealing effect can be further enhanced.

[Effect of the Invention 1] According to the present invention, since the magnetic shielding member that covers the induction heating coil is provided, the leakage magnetic flux to the outside is significantly reduced, and the induced voltage generated in the object to be heated and the roll is reduced. As a result, the number of interlinkages of the leakage magnetic flux with the heated object and the roll/\ is also significantly reduced, arcing due to induced voltage is no longer generated, and the generation of spark marks can be suppressed.

Furthermore, the reduction in leakage magnetic flux improves the operating power factor of the induction heating coil, and improves overall electrical efficiency.

[Brief Description of the Drawings] Figure 141 is a side sectional view showing one embodiment of the induction heating device of the present invention, Figure 2 is a diagram showing the magnetic flux distribution by the induction heating coil in Figure 1, and Figure 3 is a diagram showing the magnetic flux distribution by the induction heating coil in Figure 1. FIG. 4 is a side sectional view of an induction heating device according to another embodiment of the present invention, and FIG. 5 is a diagram showing the magnetic flux distribution due to the induction heating coil in FIG. 3.
FIG. 6, a side sectional view of a conventional induction heating device, is a diagram showing the magnetic flux distribution by the device of FIG. 5. DESCRIPTION OF SYMBOLS 1...Metal plate, 2...Roll, 3...Induction heating coil, 4...Magnetic shield, X...Leakage magnetic flux suppression plate. Patent applicant: Mr. Ike, Sumitomo Metal Industries, Ltd.
Patent attorney: 2 people (excluding the above) *1 illustration 21gJ

Claims (2)

[Claims] (1) In a transverse magnetic flux type induction heating device in which induction heating coils are arranged on the upper and lower surfaces of a metal plate to be heated, a non-magnetic conductive member is provided to cover the outer surface of the induction heating coil to prevent leakage of magnetic flux to the outside. An induction heating device characterized by suppressed heating. (2) The conductive member according to claim 1, further comprising a non-magnetic conductive member extending outward for a predetermined length parallel to the heated metal plate at the end of the conductive member. Induction heating device.