JPS6130396B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an induction heating device for induction heating a long material such as a bar or pipe.

1 and 2 show a conventional induction heating device. In the figure, reference numeral 1 denotes a roller that supports a rod-shaped heated material 2 so that it can travel, and is supported by a support member 3 via a bearing 3a. Reference numerals 4 and 5 indicate induction heating coils (hereinafter referred to as heating coils) for inductively heating the heated material 2 supported by the roller 1, and are supported by a support base 6. 7 is an AC power source that supplies power to the heating coils 4 and 5.

When the material to be heated 2 is subjected to induction heating, the material to be heated 2 is continuously moved on the roller 1 by a drive device (not shown).

By the way, when performing induction heating, due to the coil pitch θ of the heating coils 4 and 5 shown in FIG. 3, the electromotive force generated in the heated material 2 by the heating coils 4 and 5 is As shown, this electromotive force a causes an electromotive force b, which is an axial component of the heated material 2, to be generated.

This electric power b causes a part of the eddy current flowing through the heated material 2 (hereinafter referred to as axial current) to flow between the heated material 2 and the ground 8 via the roller 1.

This axial current causes adverse effects such as deterioration of the bearing 3a of the roller 1 due to electrolytic corrosion.

Further, the axial current causes malfunction of various detectors installed in the heating line that detect the position and temperature of the material to be heated 2, and causes arcing in the material to be heated 2.

As a countermeasure against this problem, the conventional induction heating device has two heating coils 4 and 5 placed between the rollers 1 as shown in FIG. 1, and as shown in FIG.
The AC power supply 7 is arranged so that the axial components of the electromotive force generated by the heating coils 4 and 5 cancel each other out.
were connected to heating coils 4 and 5.

For this reason, conventional induction heating devices not only require multiple heating coils 4 and 5, but also
There is a drawback that the heating coils 4, 5 must be adjusted so that the axial component of the electromotive force of the heating coils 4, 5 becomes zero.

FIG. 5 shows an induction heating device according to an embodiment of the present invention. In the figures, 1 to 3 refer to figures 1 to 2.
Since it is similar to the conventional induction heating device shown in the figure, the explanation will be omitted. 9 is a heating coil that heats the heated material 2 supported by the roller 1;
Supported by. Reference numeral 11 denotes an annular iron core disposed between the heating coil 9 and the roller 1, through which the heated material 2 passes, and is formed of laminated silicon steel plates and supported by a support base 12.

In the process of heating the material to be heated 2, an axial current flows between the material to be heated 2 and the ground 8 via the roller 1 due to the axial component of the electromotive force generated by the heating coil 9. 11 is excited. Therefore, an electromotive force is generated in the heated material 2 in a direction opposite to the axial component of the electromotive force caused by the heating coil 9, and the value of the axial current becomes extremely small.

Therefore, one heating coil 9 is placed between the rollers 1.
Even if the bearing 3 of the roller 1 is
There is no risk that a will deteriorate.

6 and 7 show an induction heating device used as an annealing device according to another embodiment of the present invention.

A V-shaped roller 13 is supported by a support member 14 via a bearing 14a. A pipe 15 is supported by the rollers 13, and has a welded portion 15a seam-welded in the axial direction at the upper part. 16 is a first support frame arranged at a position intermediate between the rollers 13; 17 is a first support frame 16;
a second support frame that is movably supported by 1;
Reference numeral 8 indicates a heating coil disposed facing the welding portion 15a and supported by the second support frame 17; numeral 19 indicates an annular iron core disposed between the heating coil 18 and the roller 13, through which the pipe 15 passes; It is formed of laminated silicon steel plates and is supported by a support stand 20.

When annealing the welded portion 15a using the induction heating device, the second support frame 17 is lowered to bring the heating coil 18 close to the welded portion 15a, and the heating coil 18
The pipe 15 is caused to run in the axial direction while being energized.

An eddy current flows through the welded portion 15a due to the electromotive force caused by the action of the current flowing through the heating coil 18, and the welded portion 15a is heated and annealed by this eddy current.

By the way, during the period when the welding part 15a is heated, an axial current flows between the pipe 15 and the ground 8 via the roller 13 due to the axial component of the electromotive force, and this axial current causes the iron core to 19 is excited. When the iron core 19 is excited, an electromotive force is generated in the pipe 15 in a direction opposite to the axial component of the electromotive force caused by the heating coil 18, and the axial current becomes extremely small.

Therefore, there is no possibility that the bearing 14a of the roller 13 or the like will be deteriorated due to electrolytic corrosion caused by the shaft current.

It should be noted that the iron core 19 can also be effectively placed on one side of the heating coil 18.

Further, the present invention produces similar effects even when used in a pipe suturing process. Furthermore, similar effects can be obtained even when a plurality of heating coils are installed on the same feeding line.

As described above, since the induction heating device of the present invention is provided with an iron core through which the material to be heated is passed through, the axial current This has the effect of reducing deterioration due to electrolytic corrosion of the bearings of the rollers that support the material to be heated.

[Brief explanation of the drawing]

Figures 1 and 2 show a conventional induction heating device.
FIG. 1 is a side view, and FIG. 2 is a circuit diagram. FIG. 3 is an explanatory diagram for explaining the electromotive force of the heating coil,
FIG. 4 is a vector diagram of electromotive force, FIG. 5 is a side view of an induction heating device according to an embodiment of the present invention, and FIGS. 6 and 7 are illustrations of induction heating devices according to other embodiments of the invention. FIG. 6 is a side view, and FIG. 7 is a front view. In the figure, 1 is a roller, 2 is a heated material, 3 is a support member, 9 is a heating coil, and 11 is an iron core. In the diagram,
The same reference numerals indicate the same or equivalent parts.

Claims (1)

[Claims] 1. A pair of rollers that movably support a rod-shaped material to be heated, a heating coil that is arranged between the two rollers and heats the material to be heated by induction, and a heating coil that is arranged between the heating coil and at least one of the rollers, An induction heating device including an annular iron core through which the material to be heated is penetrated by the heating coil.