JPS62262386A - Induction heater - Google Patents

Abstract

(57) [Summary] 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 heating a slab, for example.
In particular, the aim is to reduce stray loss and noise in the furnace frame of the heating device.

(Prior Art) In this type of conventional induction heating device, as shown in FIG. 3, for example, the side surface of a furnace frame A is configured in a lattice shape with a horizontal member 1 and a vertical member 2 integrally attached at right angles. An insulating support 3 is placed on the inner surface of the furnace frame A at a position facing the vertical member 2 and is integrally fixed to the furnace frame A, and this insulating support 3 is used to form a rectangular shape centered between the furnace frame A. A device having heating coils 4 arranged therein is known from Japanese Utility Model Publication No. 52-31449.

For example, when heating a slab, such an induction heating device inserts the slab into the heating coil 4, energizes the heating coil 4, and uses the magnetic flux generated by the heating coil 4 to cause an induced current to flow through the slab. The slab is heated by Joule heat. Also, the leakage magnetic flux of the heating coil 4 is
It goes out from the inside of the heating coil 4 and returns to the heating coil 4 again via a structure such as the furnace frame A located outside the heating coil 4. Therefore, a large induced current also flows through the furnace frame A, but since the furnace frame A is generally made of steel or the like with high rigidity, a stray loss occurs in the furnace frame A and the temperature of the furnace frame A increases.

Therefore, in order to reduce such stray loss, an iron core made of laminated silicon steel plates is placed on the outer circumferential side of the heating coil 4.
The structure that guides the leakage magnetic flux to this iron core is, for example, the Utility Model Act of 1973-4.
It is known from No. 3012. That is, as shown in FIG. 4, a plurality of insulating columns 3 and iron cores 5 are arranged alternately orthogonally to the furnace frame A on the inner wall of the furnace frame A, and these insulating columns 3 and iron cores 5 are used. The structure supports a rectangular heating coil 4 arranged concentrically with the furnace frame A.

[Problem that the invention seeks to solve]

As mentioned above, in conventional induction heating devices, an iron core is provided outside the heating coil in order to reduce stray tn generated in the furnace frame, but if the magnetic flux density of this iron core is high, iron m will increase. Furthermore, since leakage magnetic flux also increases, the effect of providing an iron core is halved. Therefore, if a structure is adopted in which the cross-sectional area of the iron core is increased and the number of iron cores is increased in order to reduce the magnetic flux density, the device becomes larger and the overall weight increases.

Further, as the number of iron cores increases, the number of components supporting the iron core increases, resulting in problems such as maintenance and inspection performance being hindered. Furthermore, the noise generated by the vibration of the iron core becomes extremely large, causing problems such as noise pollution during work or in the surrounding area.

In view of the above-mentioned problems, it is an object of the present invention to provide an induction heating device with less stray m in the furnace frame, with a simple structure, without increasing the amount of ffi, and with less noise.

Means for Solving Problem C] The induction heating device of the present invention has a heating device that faces the second frame member of the furnace frame,
A short-circuiting coil made of a conductive metal such as a copper strip plate is installed inside the furnace frame, and a short-circuit coil is installed inside the furnace frame.
The frame material is made of non-magnetic metal.

[Effect]

The magnetic flux generated by the heating coil causes a large induced current to flow through the slab inserted into the heating coil, heating the slab with Joule heat. The leakage magnetic flux of the heating coil interlinks with the short-circuit coil provided on the axial end side of the heating coil, causing an induced current to flow through the short-circuit coil.

The induced N current flowing through the short-circuited coil generates a repulsive magnetic field, which changes the direction of the magnetic flux leaking from the heating coil.

Therefore, leakage magnetic flux does not flow into structures such as the furnace frame, so that adverse effects do not occur, and the first frame material of the furnace frame is made of non-magnetic metal, reducing stray loss.

Furthermore, since no iron core is used to form a magnetic path for leakage magnetic flux, the device is lightweight and the problem of noise is eliminated.

〔Example〕

The present invention will be explained in detail below with reference to drawings showing embodiments thereof. FIG. 1 is a front vertical sectional view of an induction heating device according to the present invention. In Fig. 1, the side frame of the furnace frame A is in the front-back direction (
The vertical parts (O 6), which are the first frame members made of non-magnetic metal such as stainless steel and aluminum, and the upper and lower ends of these vertical members 6 are arranged in parallel at appropriate lengths apart from each other in the front and back directions of the paper. It is framed by a horizontal member 1, which is a second frame member, which is integrally attached at right angles to the vertical member 6.The side frames constructed in this way are assembled into a rod shape on four sides to form a furnace. Assembling frame A.

Near the center in the length direction of the vertical member 6 of the left and right side frames, two insulating support members 7 of equal length with appropriate length and shortness are spaced apart by an appropriate length in the length direction of the vertical member 6 and are installed inside the furnace frame A. It is installed to extend towards. A heating coil 4 formed by winding a wire-wound conductor into a rectangular tube shape and arranged concentrically with the furnace frame A is attached to the insulating support member 7, and the axial direction of the heating coil 4 is parallel to the vertical member 6. are doing. The upper and lower ends of the heating coil 4 are located closer to the center in the length direction of the vertical member 6 by an appropriate length than the position where the horizontal member 1 is provided.

In addition, an upper short-circuit conductor 8 and a lower short-circuit conductor 9, which are close to both the upper and lower axial ends of the heating coil 4 and have one turn with the same dimensions so as to face the heating coil 4, are placed concentrically with the heating coil 4. It is placed opposite to.

Inside the furnace frame A at the upper and lower ends of the vertical member 6, facing the horizontal member 1, there is a slightly thicker copper strip having a height equal to the height of the horizontal member 1. Wind the plate along the furnace frame A in a rectangular spiral shape with a predetermined number of turns,
An upper short-circuit coil 10 and a lower short-circuit coil 11 are provided, respectively, in which the winding start end and the winding end end are connected and short-circuited,
It is supported on the furnace frame A by appropriate attachment means. That is,
The upper opening and lower opening of the furnace frame A are covered by an upper shorting coil 10 and a lower shorting coil 11. Similarly, at the height position of the longitudinal center of the vertical member 6,
An intermediate short-circuit coil 12 having a predetermined number of turns is disposed between the inside of the furnace frame A and the heating coil 4. This short circuit coil 12 is supported and attached to the furnace frame A by appropriate means. Note that 13 is a heated material such as a slab inserted inside the heating coil 4.

The state of leakage magnetic flux in the induction heating device configured as described above will be explained with reference to FIG. 2, which schematically shows the flow of magnetic flux.

FIG. 2 is a right half sectional view of the induction heating device when viewed from the front.

By energizing the heating coil 4, the magnetic flux generated by the heating coil 4 passes through the heated material 13, but the leakage magnetic flux φ interlinks with the upper short-circuit conductor 8 and generates a repulsive magnetic field.

The leakage magnetic flux Φ changes its direction due to the repulsion magnetic field generated by the upper short-circuit conductor 8 and passes between the upper short-circuit conductor 8 and the heating coil 4 and heads toward the upper horizontal member 1, but the leakage magnetic flux Φ is directed to the upper horizontal member 1 provided above the furnace frame. The upper shorting coil 10 is connected to the upper shorting conductor 8.
By generating a repulsive magnetic field similar to the repulsive magnetic field at Due to the same repulsive magnetic field of the intermediate short circuit coil 12, the magnetic field changes direction and enters the inner peripheral side of the intermediate short circuit coil 12, and then enters the vertical member 6 again. Then, at the position reaching the lower side of the vertical member 6, the direction is changed by the anti-QMI field caused by the lower short circuit coil 11 and the heating coil 4 is pushed back upward.
As in the case at the upper end, it passes between the lower end of the heating coil 4 and the lower short-circuit conductor 9 and returns to the inner peripheral side of the heating coil 4. Note that the magnetic flux Φ flows in the same manner on the other left half side of the heating coil 4 (not shown).

By the way, the amount of magnetic flux generated in the heating coil 4 is
3, the leakage magnetic flux φ passing through the outside of the heating coil 4 has almost no influence, that is, the leakage magnetic flux of the heating coil 4 is approximately constant. Therefore, the induced M current flowing through the upper and lower shorting conductors 8.9, the upper and lower shorting coils 10.11 and the intermediate shorting coil 12 is , furthermore, the horizontal member 1 in the absence of the intermediate short-circuit coil 12
．． It is approximately equal to the induced current flowing through 1. Therefore, the upper and lower shorting conductors 8.9 and the upper, lower and intermediate shorting coils 1, respectively.
By constructing L12 with a copper strip having a low resistance value, for example, the Joule heat generated therein is extremely reduced.

Therefore, the upper and lower short circuit conductors 8, 9 and the upper, lower and intermediate short circuit coils! 0.0, 11.12 temperature rise can be significantly suppressed. Furthermore, since there is no iron core that forms a magnetic path for leakage magnetic flux, no electromagnetic vibration occurs and noise is extremely reduced. Furthermore, at a position where there is no intermediate short circuit coil 12,
Magnetic flux Φ enters the vertical member 6, but since the vertical member 6 is made of non-magnetic metal, the amount of magnetic flux flowing in is small, the resulting temperature rise is small, and stray 772 t) IJU is extremely small.

In the above-mentioned embodiment, copper strips were used for the upper and lower shorting conductors 8°9 and the upper, lower and intermediate shorting coils IO, 11, 12, but steel pipes or steel pipes could also be used. good,
In addition, upper and lower short circuit conductors 8 and 9 and intermediate short circuit coil 12
If the conductor has a structure that allows water to flow inside the conductor and its temperature rise is further suppressed, the increase in resistance value can be further suppressed and almost no temperature rise will occur.

Furthermore, although the upper and lower short-circuit conductors 8.9 are made into one turn, they may be made into several turns.

Furthermore, in the embodiment, the shorting conductors 8.9 are provided close to both ends of the heating coil 4, but even if they are not provided, there is no significant difference in effect.

〔effect〕

As described in detail above, the inner peripheral side of the furnace frame, facing the second frame material constituting the furnace frame, and the axially intermediate position of the heating coil, and the space between the heating coil and the furnace frame, respectively. A simple structure in which a short-circuit coil is provided and non-magnetic metal is used for the first frame material that makes up the furnace frame suppresses stray loss in the furnace frame and increases the temperature of the furnace frame without increasing the size of the device. can be prevented. Furthermore, since no iron core is used to form a magnetic path for leakage magnetic flux, there is no noise caused by electric RA vibration, and a low-noise induction heating device with less stray M loss can be provided.

4. r! ! Brief explanation of J-plane FIG. 1 is a front vertical sectional view of the induction heating device according to the present invention;
FIG. 2 is a right half-cut sectional view of the induction heating device showing the state of leakage magnetic flux, and FIGS. 3 and 4 are external perspective views of the conventional induction heating device.

l...Second frame material 4...Heating coil 6...First
Frame material 8... Upper short circuit conductor 9... Lower short circuit conductor 1
0... Upper short circuit coil 11... Lower short circuit coil
12... Intermediate short-circuit coil A... Furnace frame In the drawings, the same reference numerals indicate the same or equivalent parts.

Patent Applicant Mitsubishi Electric Co., Ltd. Agent Patent Attorney Masuo Oiwa and 2 others 1 --- Atsushi Z) F Omote.

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Claims (1)

[Scope of Claims] 1. A furnace frame composed of a first frame member made of non-magnetic metal and a second frame member attached perpendicularly to both ends of the first frame member; A heating coil disposed inside the furnace frame in parallel with the frame material, a short-circuiting coil facing the second frame material and disposed inside the furnace frame, and a heating coil arranged in the middle of the heating coil in the axial direction. An induction heating device characterized by comprising a short circuit coil disposed between the furnace frame and the furnace frame. 2. The induction heating device according to claim 1, wherein the short circuit coil is formed of a copper strip, a steel pipe, or a copper stranded wire. 3. The induction heating device according to claim 1, wherein the short circuit coil has a forced water cooling structure.