JPH05163521A - Vertical type induction heating apparatus - Google Patents

Abstract

PURPOSE:To obtain the uniform heating of a slab by restraining the radiation of heat from the end parts of a charged slab. CONSTITUTION:Movable walls 5 as a heat radiation preventing plate are arranged so as to be possible to face to the end surfaces of the charged slab 1 at the front sides of furnace walls 2a in the longitudinal direction in a furnace body 2. The movable wall 5 is composed of plate-like refractory heat insulating material so as to be possible to shift in the longitudinal direction of the furnace body 2. At the furnace wall 2a side of this movable wall 5, a supporting body for supporting while hanging up this movable wall 5 is fixed. This supporting body is made to advance/retreat the movable wall 5 toward the longitudinal direction of the furnace body 2. i.e., the end surface in the longitudinal direction of the charged slab 1 through a water cooling pipe 6a by driving a cylinder device 7.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vertical induction heating device for heating a slab to a temperature suitable for rolling during hot rolling, and more particularly, to a uniform loading of the loaded slab along the longitudinal direction. The present invention relates to a vertical induction heating device having a heating means.

[0002]

2. Description of the Related Art In a vertical induction heating apparatus, an induction heating coil is provided on the outer periphery of a furnace body made of a box-shaped refractory heat insulating material into which slabs whose width direction is up and down can be loaded from below. The induction heating coil is adapted to inductively heat the slab charged in the furnace body.

At this time, the end of the slab in the longitudinal direction has a temperature lower than that of the center because the current density of the induced current is small and the amount of heat generated is small, and the loss due to heat dissipation from the end face is large. Is big. In particular, when a short slab is charged, the distance between the end surface of the slab and the furnace wall is large, the heat dissipation from the end is large, and the temperature difference between the central portion in the longitudinal direction and the end is further increased.

In order to solve this problem and achieve uniform heating of the slab, in the past, for example, Japanese Patent Publication No. 53-9.
As described in Japanese Patent No. 433 publication, a dummy metal plate is arranged as a heating element so as to be close to the end surface of the inserted slab, and is also described in Japanese Utility Model Laid-Open No. 63-72888. As described above, by constructing the furnace wall facing the inserted slab end from a plurality of refractory heat-insulating materials capable of rotating 90 degrees, it is possible to suppress the heat radiation from the slab end and to uniformly heat the slab. I was trying to achieve it.

[0005]

However, in the method of disposing the dummy metal plate, the side facing the slab becomes hotter than the side facing the furnace wall during induction heating,
This temperature difference causes a difference in the amount of elongation on both sides, causing the metal plate to warp. As a result, there is a problem that the warped metal plate is likely to damage the furnace wall or interfere with the slab when the slab is charged.

Further, in the method of using the rotatable refractory heat insulating material, the rotating portion of the refractory heat insulating material is close to the inside of the furnace (slab side), so that it is easily thermally deformed, and the rotating portion is generated during heating. There is a problem that the melted scale and the like are easily caught or welded, which makes it difficult to rotate. Further, there is a problem that the furnace wall positions that can be installed are limited to a few places, and a sufficient effect is not always obtained as heat retention at the slab end.

The present invention has been made in view of the above problems, and it is an object of the present invention to realize uniform heating of a slab by suppressing the dissipation of heat from the end of the loaded slab. ..

[0008]

In order to achieve the above object, a vertical induction heating apparatus of the present invention is provided in a box-shaped furnace body into which a slab is charged from below, and on the outer periphery of the furnace body. In a vertical induction heating device equipped with an induction heating coil,
Between the longitudinal end surface of the slab charged in the furnace body and the furnace wall, a heat dissipation preventive plate made of a fireproof heat insulating material is disposed with one surface facing the end surface of the slab, and the heat dissipation preventive plate. It is characterized in that a means for advancing and retreating toward the end face of the slab is provided.

[0009]

In the prior art, at the longitudinal end portion of the slab, in addition to the heat radiation from the side surface in the longitudinal direction, there is heat radiation from the end surface, so that the temperature drop is larger than at the central portion in the longitudinal direction. On the other hand, in the present invention, in order to prevent heat radiation from the end surface of the slab, before the induction heating of the slab, the heat radiation prevention plate is moved toward the end surface of the slab to move the heat radiation prevention plate to the slab. Press on the end face of.

As a result, when the slab is heated, the heat radiation preventing plate is in close contact with the longitudinal end face of the slab, so that heat radiation from the end face is suppressed. Therefore, due to the heat radiation from the end face of the slab, the temperature of the longitudinal end portion, which is lower than the temperature in the longitudinal central portion, approaches the same temperature as the longitudinal central portion, and the slab moves along the longitudinal direction. And evenly heated.

Since the heat dissipation plate is made of a fireproof heat insulating material, it does not generate heat and warp unlike a metal plate.

[0012]

Embodiments of the present invention will be described with reference to the drawings.
First, the structure will be described. As shown in FIGS. 1 and 2, an induction heating coil 3 is arranged on the outer periphery of a furnace body 2 made of a refractory heat insulating material into which the slab 1 can be loaded. The induction heating coil 3 is connected to an induction power source 4 and electric power is supplied from the induction power source 4.

In front of the furnace wall 2a in the longitudinal direction in the furnace body 2, a moving wall 5 which constitutes a heat radiation preventing plate is arranged so as to be able to face the end surface of the inserted slab 1. The moving wall 5
Is made of a plate-shaped refractory heat insulating material having substantially the same size as the furnace wall 2a, and is movable along the longitudinal direction of the furnace body 2. The moving wall 5 is located on the furnace wall 2a side of the moving wall 5.
A support body that suspends and supports is fixed.

The support is composed of two double pipe type water cooling pipes 6a.
The water cooling pipe 6a is fixed to the moving wall 5 with its axis vertically and extends upward, and projects upward from the furnace body 2 through an opening 2b opened in the ceiling of the furnace body 2. .. The upper portions of the two water cooling pipes 6a are connected to a horizontal member 6b, and a cylinder device 7 having a horizontal axis is provided at the center of the horizontal member 6b.
End portions of rods 7a are connected to each other, and by moving the cylinder device 7, the moving wall 5 moves back and forth through the water cooling pipe 6a toward the longitudinal direction of the furnace main body 2, that is, toward the end face in the longitudinal direction of the loaded slab 1. It is like this.

When the water cooling pipe 6a is installed on the slab 1 side of the moving wall 5, heat removal from the slab 1 is increased. Therefore, the water cooling pipe 6a is arranged on the furnace wall 2a side and the moving wall 5 is moved to the slab 1 side. Sufficient thickness is secured. If the water-cooling pipe 6a is not heated more than a predetermined amount, a water-cooling structure is not necessary, so a metal rod or the like may be applied, or ceramics or the like that does not generate heat may be used.

At the opening 2b provided in the ceiling of the furnace main body 2, there is provided a box body 8 having an open lower surface for sealing the atmosphere in the furnace. In the induction heating device as described above, the slab 1 is placed on the hearth 9 with the width direction thereof being up and down, and the hearth 9 is lifted to move the slab 1 into the furnace from the charging port of the furnace body 2. Charge.

After the slab 1 is loaded into the furnace, the cylinder device 7 is driven to move the moving wall 5 to the slab end face 1a side and bring the moving wall 5 into close contact with the slab end face 1a. In this state, electric power is applied to the induction heating coil 3 from the induction power source 4 to induction-heat the slab 1. At this time, since the slab 1 charged in the furnace thermally expands as it is heated, in practice, the moving wall 5 is separated from the slab end face 1a by a predetermined amount by the thermal expansion amount, or It is advisable to allow the moving wall 5 to move backward following the expansion.

In this way, by the moving wall 5,
In the heated slab 1, heat radiation from the end face in the longitudinal direction is suppressed, and the temperature distribution in the longitudinal direction of the slab 1 becomes uniform.
In order to confirm this, the heating target temperature is set to 1350 ° C., the slab 1 having a thickness of 220 mm × a width of 1000 mm × a length of 12000 mm is used as an induction heating device based on the above-mentioned embodiment and a conventional induction heating device for comparison. As for the temperature distribution when heated in, the temperature distribution along the longitudinal direction of the slab at the widthwise central portion was measured, and the results shown in FIG. 3 were obtained. In FIG. 3, the solid line shows the temperature distribution based on the present embodiment, and the dotted line shows the temperature distribution according to the conventional device.

As is apparent from the figure, the temperature drop at the end portion of the slab 1 is reduced as compared with the conventional case, and the heating is performed substantially uniformly. It should be noted that the difference in the amount of temperature decrease at the right end portion in the figure is smaller than that in the conventional example and the present embodiment, because one end portion of the furnace wall when the slab is charged as shown in FIG. This is because the moving wall 5 and the means for driving the moving wall 5 are provided only on one side, and the slab 1 is placed close to the other furnace wall 2a depending on the target accuracy. ..

The surface of the moving wall 5 facing the slab 1 may have a size enough to cover the end surface of the slab 1, and the shape thereof is not limited to the flat plate shape. Other shapes such as a U-shaped cross-section that surrounds the ends of the facing slabs 1 may be used. However, when the U-shaped cross section is used, it is necessary to sufficiently consider the change in the thickness of the slab 1, the amount of inclination of the slab 1, and the like.

Further, in the above embodiment, the moving wall 5 is moved by using the cylinder device 7. However, a rail is provided laterally in the box body 8 and the rail is movable from the carriage movable along the rail. The wall 5 is hung, and the moving wall 5 is moved,
You may comprise the advancing / retreating means which moves the moving wall 5 by another well-known means. Further, in the above embodiment, the moving wall 5
Is hung from above and moved, but a guide is provided on the hearth 9 in the longitudinal direction, and a movable wall 5 is installed so as to be movable along the guide provided on the floor, and the hearth is placed before entering the furnace. The moving wall may be brought into contact with the longitudinal end surface of the slab 1 mounted on the furnace and then charged into the furnace.

[0022]

As described above, in the vertical induction heating apparatus of the present invention, the refractory heat insulating material is pressed against the longitudinal end face of the loaded slab, so that heat radiation from the end is suppressed. The effect is that uniform heating of the slab is improved.

[Brief description of drawings]

FIG. 1 is a side sectional view showing a vertical induction heating apparatus according to an embodiment of the present invention.

FIG. 2 is a top view of the same except for the box and the ceiling of the furnace body.

FIG. 3 is a diagram showing a temperature distribution in the longitudinal direction of a heated slab.

[Explanation of symbols]

 1 Slab 2 Furnace body 3 Induction heating coil 5 Moving wall (heat dissipation prevention plate) 6a Water cooling pipe 7 Cylinder device

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inoue Hiroshi Shimogumi 1-chome, Mizushima Kawasaki-dori, Kurashiki City, Okayama Prefecture (no address) Inside the Mizushima Works, Kawasaki Steel Co., Ltd. (72) Kenji Torigoe Mizushima, Kurashiki City, Okayama Prefecture Kawasaki Dori 1-chome (no house number) Kawasaki Steel Co., Ltd. Mizushima Steel Works (72) Inventor Kazuaki Hara Mizushima, Kurashiki City, Okayama Prefecture Kawashima Dori 1 chome house (no house number) Kawasaki Steel Co., Ltd. Mizushima Steel Works

Claims (1)

[Claims] 1. A vertical induction heating apparatus comprising a box-shaped furnace main body into which a slab is charged from below and an induction heating coil arranged on the outer periphery of the furnace main body. The heat radiation preventing plate made of a refractory heat insulating material is disposed with one surface facing the end face in the longitudinal direction of the slab, and the advancing / retreating means for moving the heat radiation preventing plate back and forth toward the end face of the slab. Vertical induction heating device.