JP3616202B2 - Induction heating device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an apparatus for automatically detecting cracks in a heat insulating plate that protects the surface of an apparatus for induction heating of a material to be heated that is continuously conveyed.
[0002]
[Prior art]
In general, an induction heating apparatus that continuously heats and heats a material to be heated, such as a steel rolling line, is conventionally configured as shown in FIG. In this induction heating device, a water-cooled copper pipe is wound around a concave groove 3 between legs 2 and 2 of a laminated iron core 1 to form a heating coil 4, and an amorphous heat insulating material 5 is molded into the concave groove 3. Further, the heat insulating plate 6 is attached to the surface and supported by the support frame 7.
[0003]
This induction heating apparatus is installed so as to sandwich both end sides of the material to be heated 8 from above and below, and locally heats both end portions having a large temperature drop. In this case, the smaller the gap between the induction heating device and the material to be heated 8 is, the better the heating efficiency is. Therefore, the collision with the material to be heated 8 is usually prevented and the heating efficiency is taken into consideration. ing.
[0004]
For this reason, the heat insulating plate 6 is attached to the surface in order to protect the heating coil 4 from the radiant heat of the heated material 8 that has been induction-heated. Heated to ˜1300 ° C. The heat insulating plate 6 is formed of a heat-resistant castable cement or ceramic fired plate having excellent fire resistance. However, since the inner heating coil 4 is water-cooled during operation, the heat insulating plate 6 has a large surface and inner surface. In addition to causing a temperature difference, the heated material 8 or oxide scale collides with the surface and gradually damages. For this reason, since the thermal insulation plate 6 is subjected to a shock while being used for a long time, a crack is generated in the heat insulating plate 6, and when this proceeds, the radiant heat enters through the crack and finally the insulation coating of the heating coil 4 May cause a short circuit between the coils.
[0005]
In order to prevent this, the operation is stopped and periodically inspected to reconstruct the heat insulating plate 6. When the heat insulating plate 6 is formed of heat insulating castable cement, the operation must be stopped for a long time, such as dismantling, reconstructing, and drying. Moreover, since the thing which formed the heat insulation board 6 with the ceramic baking board should just replace | exchange only a board, the time which stops operation can be shortened.
[0006]
However, there is no method for confirming whether or not the heat insulating plate 6 has been cracked during operation. Normally, it is visually confirmed when the line is stopped, but if a thin crack has occurred, it should be detected reliably. Once the short-circuit accident occurs, there is a problem that the operation must be stopped for a long time, such as replacement of the heating coil 4 and refilling of the irregular heat insulating material 5.
[0007]
[Problems to be solved by the invention]
An object of the present invention is to provide an induction heating device that eliminates the above-mentioned drawbacks and can automatically detect the occurrence of cracks in a heat insulating plate at a remote location to prevent a short-circuit accident due to dielectric breakdown of a heating coil. It is what.
[0008]
[Means for Solving the Problems]
The induction heating device of the present invention is an induction heating device in which a water-cooled heating coil is wound around a leg portion of an iron core, and a heat insulating plate is coated on the surface of the material to be heated. In addition, a detection line that is heated to a high temperature due to cracking of the heat insulating plate is disconnected , and this detection line is connected to the power supply and the display. When the detection line is disconnected, the current from the power supply is cut off and the display Is activated and the occurrence of cracks in the heat insulating plate is detected .
[0009]
In the induction heating device having the above-described configuration, when a heating coil is energized from a high-frequency power source, a magnetic flux is generated, and this heats the material to be heated on which it continuously runs. At this time, the heat insulating plate on the surface is heated by radiant heat from the heated material heated to a high temperature. When a crack occurs in the heat insulating plate during operation, the thin thin detection wire is radiated from the material to be heated through the crack and is heated to a high temperature to break. When the detection line breaks, the current from the power supply is cut off, and the display is activated to notify that the insulation board has cracked.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described in detail with reference to FIGS. As shown in FIG. 1, this induction heating device forms a heating coil 4 by winding a water-cooled copper tube in a concave groove 3 between legs 2 and 2 of a laminated core 1, and the concave groove 3 is indefinite. The heat insulating material 5 is molded, and a ceramic heat insulating plate 6 is further attached to the surface of the heat insulating material 5 and supported by the support frame 7. Up to this point, the structure is the same as the conventional structure shown in FIG.
[0011]
Further, inside the ceramic heat insulating plate 6, as shown in FIG. 2, detection lines 9 are meandered and embedded integrally, and both ends of these detection lines 9 are drawn out of the support frame 7, Connected to the display 11. The display 11 displays an alarm when the circuit of the detection line 9 is interrupted.
[0012]
When heating the ends of the heating member 8 in the apparatus, the first current from the high-frequency power supply (not shown) to the heating coil 4, that through transmural material to be heated 8 this magnetic flux is generated is continuously running vertically. At this time, Joule heat is generated by the eddy current generated in the material to be heated 8, and both ends of the material to be heated 8 are heated. At this time, since the material to be heated 8 continuously passes close to the ceramic heat insulating plate 6 on the surface, the ceramic heat insulating plate 6 is heated by the radiant heat from the material to be heated 8. In this state, the detection wire 9 embedded inside is insulated from the front side by the ceramic heat insulating plate 6 and cooled from the back side by the water-cooled heating coil 4 to keep the temperature low . Further, since the detection line 9 is closed and energized from the power source 10, the display 11 does not operate.
[0013]
When a crack 12 occurs in the ceramic heat insulating plate 6 during operation, the thin detection wire 9 embedded and wired inside receives heat from the heated material 8 through the crack 12 and heats it to a high temperature. Has been disconnected. When the detection line 9 is disconnected, the current from the power source 10 is cut off and the display 11 is activated to notify that the crack 12 has occurred in the heat insulating plate 6. Thus, when the generation | occurrence | production of the crack 12 is detected, repair and replacement | exchange of the ceramic heat insulation board 6 can be performed, and the dielectric breakdown of the heating coil 4 can be prevented.
[0014]
Note that the magnetic flux generated from the heating coil 4 passes through the detection wire 9, but the detection wire 9 is formed of a thin metal wire, so that it is rarely heated by induction heating itself. Further, since the detection wire 9 is embedded inside the heat insulating plate 6, the strength is increased and the durability can be further improved.
[0015]
Moreover, the wiring method of the detection line 9 is not limited to the meandering shape, and may be a spiral shape as shown in FIG. The heat insulating plate 6 is not limited to a ceramic fired plate, and may have a structure formed of heat insulating castable cement. Further, when the heat insulating plate 6 is molded, if a fiber thread or the like is embedded, the durability can be further improved.
[0016]
【The invention's effect】
As described above, according to the present invention, with a simple structure in which a detection line is wired on the back side or inside of the heat insulating plate, the occurrence of a crack in the heat insulating plate is electrically detected at a remote place, and repair or replacement is performed. An induction heating device that can prevent a short-circuit accident due to insulation breakdown of the heating coil can be obtained.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view showing an induction heating device according to an embodiment of the present invention.
FIG. 2 is a plan view showing a wiring state of detection lines attached to the back surface of the heat insulating plate shown in FIG.
FIG. 3 is an enlarged cross-sectional view showing a state in which the heat insulating plate shown in FIG. 1 is cracked.
FIG. 4 is a plan view showing a state in which detection lines according to another embodiment of the present invention are spirally wired.
FIG. 5 is a longitudinal sectional view showing a conventional induction heating apparatus.
[Description of marks Nos.]
DESCRIPTION OF SYMBOLS 1 Iron core 2 Leg part 3 Concave groove 4 Heating coil 5 Heat insulating material 6 Heat insulating board 7 Support frame 8 Heated material 9 Detection line
10 Power supply
11 Display
12 crack

Claims (1)

Winding a heating coil which is cooled to the legs of the core, the induction heating device coated with insulation plate on the surface of the material to be heated side, over the inner or back side of the whole surface of the insulating plate, the cracking of the insulating plate Connect a detection line that breaks when heated to a high temperature, connect this detection line to the power supply and the display, and if the detection line breaks, the current from the power supply is cut off and the display is activated, and the insulation plate cracks. An induction heating device characterized by detecting the occurrence of the above .

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