JPH0576146B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an induction heating device for heating a slab, for example, and is particularly intended to reduce stray loss and noise in the furnace frame of the heating device.

[Prior art]

In this kind of conventional induction heating device, for example, as shown in FIG. An insulating strut 3 is placed on the inner surface of the furnace at a position facing the vertical member 2 and is integrally fixed to the furnace frame A. Using this insulating strut 3, a rectangular heating coil 4 arranged concentrically with the furnace frame A is installed. The arrangement and configuration is known from 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 applies an induced current to the slab using the magnetic flux generated by the heating coil 4. The slab is heated by the heat of the sink. Further, the leakage magnetic flux of the heating coil 4 exits from the inside of the heating coil 4 to the outside, and returns to the heating coil 4 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, a structure is known, for example, from Utility Model Publication No. 52-43012, in which an iron core made of laminated silicon steel plates is arranged on the outer circumferential side of the heating coil 4, and leakage magnetic flux is guided to this iron core. ing.
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. It has a structure in which a rectangular heating coil 4 that is arranged concentrically with the furnace frame A is supported.

[Problem that the invention seeks to solve]

As mentioned above, in conventional induction heating equipment, an iron core is provided outside the heating coil in order to reduce stray loss occurring in the furnace frame, but if the magnetic flux density of this iron core is high, iron loss 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.

SUMMARY OF THE INVENTION In view of the above problems, it is an object of the present invention to provide an induction heating device that has less stray loss in a furnace frame, has a simple structure, does not increase weight, and produces less noise.

[Means for solving problems]

In the induction heating device of the present invention, the leakage magnetic flux of the heating coil disposed within the furnace frame can be reduced by using the first The short-circuit coil, the second short-circuit coil disposed on the other shaft end side, and the third short-circuit coil disposed between the heating coil and the furnace frame in the middle of the heating coil in the axial direction The structure is configured so that it does not reach the furnace frame.

[Effect]

The magnetic flux generated by the heating coil causes a large induced current to flow through the slab inserted into the heating coil, thereby heating the slab with Joule heat. The leakage magnetic flux of the heating coil interlinks with the first short-circuit coil and the second short-circuit coil provided at each axial end side of the heating coil, and
An induced current is passed through the short circuit coil and the second short circuit coil. The induced current flowing through the first short-circuit coil and the second short-circuit coil generates a repulsive magnetic field to change the direction of the magnetic flux leaking from the heating coil. Further, the leakage magnetic flux of the heating coil also interlinks with the third short circuit coil, and an induced current flows through the third short circuit coil. A repulsion magnetic field is generated by the induced current flowing through the third short-circuit coil, and the leakage magnetic flux of the heating coil changes its direction so as to pass through the inner peripheral side of the third short-circuit coil. This prevents leakage magnetic flux from flowing into structures such as the furnace frame, and no stray loss occurs. Furthermore, the first frame material of the furnace frame is made of non-magnetic metal, reducing stray loss.

〔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 frames of the furnace frame A are vertical members that are first frame members made of non-magnetic metal such as stainless steel or aluminum and are arranged in parallel at appropriate lengths in the front-back direction (front and back direction of the page). 6, and a horizontal member 1, which is a second frame member, which is integrally attached to the vertical member 6 so as to extend over the upper and lower ends of the vertical member 6 and intersect with the vertical member 6 at right angles. Then, the furnace frame A is assembled into a frame shape using the four sides of the side frames configured in this manner. 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 this 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. Also, one of the same dimensions is placed close to both the upper and lower ends of the heating coil 4 so as to face the heating coil 4.
An upper short-circuit conductor 8 and a lower short-circuit conductor 9 forming turns are arranged concentrically and oppositely to the heating coil 4. Inside the furnace frame A at a position facing the horizontal member 1 provided at the upper and lower ends of the vertical member 6,
A slightly thicker copper strip plate having a height equal to the height of the horizontal member 1 is wound along the furnace frame A in a rectangular spiral shape with a predetermined number of turns, and the winding start end and winding end end An upper short-circuit coil 10, which is a first short-circuit coil, and a lower short-circuit coil 11, which is a second short-circuit coil, are provided, and are supported by the furnace frame A by appropriate mounting means. That is, the upper opening and lower opening of the furnace frame A are covered by the upper shorting coil 10 and the lower shorting coil 11. Similarly, an intermediate short-circuit coil 12, which is a third short-circuit coil, having a predetermined number of turns is installed between the inside of the furnace frame A and the heating coil 4 at a height position in the longitudinal center of the vertical member 6. It is set up. 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 as 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 to generate 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, passes between the upper short-circuit conductor 8 and the heating coil 4, and heads toward the upper horizontal member 1. The upper shorting coil 10 generates a repulsive magnetic field similar to the repelling magnetic field in the upper shorting conductor 8, and the magnetic flux Φ is pushed back downward and once enters the vertical member 6 and heads toward the lower side, but in the longitudinal direction of the vertical member 6. Due to the similar repulsive magnetic field of the intermediate short-circuiting coil 12 provided at the center of the magnetic field, the magnetic field changes direction and enters the inner circumferential side of the intermediate short-circuiting 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 repulsive magnetic field from the lower short-circuiting coil 11 and pushed back upwards, and the lower end and lower part of the heating coil 4 are It passes between the 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, since the amount of magnetic flux generated by the heating coil 4 is determined by the amount of heating of the heated material 13, it is hardly affected by the leakage magnetic flux Φ passing outside the heating coil 4. That is, the leakage magnetic flux of the heating coil 4 is approximately constant. Therefore, the upper and lower short circuit conductors 8, 9, upper,
Lower short circuit coils 10, 11 and intermediate short circuit coil 1
The induced current flowing in the horizontal members 2 is approximately equal to the induced current flowing in the horizontal members 1, 1 in the absence of the upper and lower shorting conductors 8, 9, the upper and lower shorting coils 10, 11, and the intermediate shorting coil 12. Therefore,
By constructing the upper and lower shorting conductors 8, 9 and the upper, lower, and middle shorting coils 10, 11, and 12 from low-resistance copper strips, for example, the Joule heat generated therein is extremely reduced.

Therefore, the temperature rise of the upper and lower shorting conductors 8 and 9 and the upper and lower and intermediate shorting coils 10, 11, and 12 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 the intermediate short-circuit coil 12 does not exist, 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 temperature rise due to this is small, and stray Losses are also extremely small.

In addition, in the above-mentioned embodiment, the upper and lower short circuit conductors 8 and 9 and the upper and lower short circuit coils 10 and 1
Although copper strips were used for Nos. 1 and 12, copper tubes or copper stranded wires may also be used. In addition, upper and lower short circuit conductors 8,
9 and the intermediate short-circuit coil 12 have a structure that allows water to flow inside the conductor, and if the temperature rise is further suppressed, the increase in resistance value can be further suppressed and almost no temperature rise will occur.

Further, although the upper and lower short-circuiting conductors 8 and 9 have one turn, they may have several turns.

Furthermore, in the embodiment, the shorting conductors 8 and 9 are provided close to both axial ends of the heating coil 4, but even if they are not provided, there is no significant difference in the effect.

〔effect〕

As described in detail above, the present invention provides a first short-circuit coil and a short-circuit coil disposed on each axial end side of a heating coil disposed within the furnace frame, facing the second frame member constituting the furnace frame. Two short-circuit coils and a third short-circuit coil are installed between the heating coil and the furnace frame at the axial center of the heating coil, so that leakage magnetic flux from the heating coil can be directed to the furnace frame as much as possible. In addition, the simple structure of using non-magnetic metal for the first frame material that makes up the furnace frame suppresses stray loss of the furnace frame without increasing the size of the equipment. It can prevent temperature rise. Furthermore, since no iron core is used to form a magnetic path for leakage magnetic flux, there is no noise due to electromagnetic vibration, and a low-noise induction heating device with little stray loss can be provided.

[Brief explanation of the drawing]

FIG. 1 is a front vertical sectional view of an induction heating device according to the present invention, FIG. 2 is a right half sectional view of the induction heating device showing the state of leakage magnetic flux, and FIGS. 3 and 4 are of a conventional induction heating device. It is an external perspective view. 1... Second frame material, 4... Heating coil, 6... First frame material, 8... Upper short circuit conductor, 9... Lower short circuit conductor, 10... Upper short circuit coil, 11... Lower short circuit coil, 12... Intermediate short circuit coil, A... Furnace frame,
In addition, in the figures, the same reference numerals indicate the same or equivalent parts.

Claims (1)

[Scope of Claims] 1. A furnace frame composed of a first frame member made of a 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 parallel to the material; a first short-circuit coil disposed on one shaft end side of the heating coil facing the second frame material; and the other shaft end. A second short-circuit coil disposed on the side, and a third short-circuit coil disposed between the heating coil and the furnace frame in the middle of the heating coil in the axial direction. induction heating device. 2. The induction heating device according to claim 1, wherein the short-circuit coil is formed of a copper strip, a copper tube, 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.