JPH05240584A - Vertical induction furnace - Google Patents

Abstract

PURPOSE:To obtain an induction furnace capable of heating uniformly a slab with preventing the slab from being cooled in excess from the upper edge on the furnace ceiling side. CONSTITUTION:An inner wall of a ceiling 1b of a furnace 1 is of a double-wall construction consisting of upper and lower layers. Although the upper layer is integrally formed into one body with the furnace 1 main body, the lower layer is formed separately from the furnace 1 main body and consists of lifting walls 11 which can be moved up and down in side the furnace 1. The lifting walls 11 are separated from each other by two or more support rods 9 that penetrate the ceiling 1b of the furnace 1. Each lifting wall 11 is suspended by lifting rods 12 which are movable up and down through the ceiling 1b of the furnace 1 and are connected to a lifting wall driving cylinder device 14 through a connecting member 13. A lifting driver is composed of the lifting rods 12, the connecting members 13 and the lifting wall driving cylinder device 14.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a vertical induction heating furnace for uniformly heating a slab, and particularly, in the induction heating, the heat dissipation from the widthwise upper end surface of the slab is effectively reduced. The present invention relates to a vertical induction heating furnace capable of uniform heating.

[0002]

2. Description of the Related Art Generally, a vertical induction heating furnace is used to more uniformly heat a slab heated by a normal continuous heating furnace. Conventionally, as a vertical induction heating furnace of this kind, one described in, for example, JP-A-63-166933 is known.

In this apparatus, an induction heating coil is arranged on the outer circumference of the side wall of a box-shaped furnace body, and an opening for charging and extracting a slab is provided in the lower part of the furnace body. A support hearth is located below the section. The support hearth can be moved up and down via an elevating beam.
When the furnace floor is raised and the slab is charged into the furnace, the charging part is sealed by the sealing device so that the atmosphere in the furnace is kept constant.

Further, a support rod having its axis oriented vertically extends through the top of the furnace body, and its lower end face vertically opposes the furnace floor. This support rod is connected to a lifting drive cylinder device via a connecting member and is driven in the vertical direction by the lifting drive cylinder device. The support rods are usually arranged at several places along the longitudinal direction of the furnace body.

In the above induction heating furnace, the slab is placed on the hearth with the width direction up and down, and the support rod descends to bring the lower end surface of the support rod into contact with the upper end surface of the slab to move the slab together with the hearth. It is sandwiched from above and below, the slab is raised while maintaining that state, and the slab is charged into the furnace and heated. This heating is performed by supplying an alternating current to the induction heating coil to generate an induced current on the surface of the slab and generate heat.

At this time, the refractory heat insulating member constituting the furnace wall receives the heat radiated from the surface of the slab, absorbs part of the heat, and returns the rest to the slab. By repeating this, the slab and the refractory heat insulating member influence each other and the slab is heated. Therefore, the relative distance between the slab and the refractory insulation member is an important factor for induction heating so that the temperature of the slab becomes uniform, but the space inside the furnace is usually based on the maximum size of the slab. Since the gap is designed to be secured between the slab and the fireproof heat insulating member, when heating a small slab, the distance between the end of the slab and the fireproof heat insulating member forming the inner wall of the furnace is predetermined. Will be separated from the above. Therefore, the area of the refractory heat insulating member that receives heat radiated from the end surface increases, the amount of heat absorbed by the refractory heat insulating member increases, and the temperature of the slab end becomes relatively low.

Regarding the prevention of the supercooling of the end portion due to the dimensional change of the slab, there is a conventional method, for example, Japanese Utility Model Laid-Open No. 63-07288.
The inner wall of the end of the furnace in the longitudinal direction is composed of a rotating wall as described in Japanese Patent No. 8 or the vicinity of the inner wall of the end of the furnace in the longitudinal direction as described in JP-A-49-046237. It is carried out by a method such as installing a heating material that can be raised and lowered freely.

[0008]

However, in the above-mentioned conventional vertical induction heating furnace, it is possible to prevent overcooling from the upper end of the slab width direction (furnace top side), which is caused by the difference in the size of the slab width direction. No effective countermeasures have been taken, and heat is also removed from the contact part with the support rod.Therefore, when induction heating a narrow slab, the slab top surface and furnace top There is a problem that the relative distance to the inner wall is more than a predetermined distance and excessive heat is generated from the upper end in the width direction, so that the slab cannot be heated uniformly.

In the vertical induction heating furnace described in Japanese Patent Laid-Open No. 63-166933, a plurality of support rods are properly contacted with or separated from the upper end surface of the slab during induction heating. However, this does not prevent supercooling of the entire upper end of the furnace top of the slab. The present invention has been made focusing on the above problems,
An object of the present invention is to provide an induction heating furnace capable of uniformly heating the slab by preventing supercooling from the upper end of the slab on the furnace top side.

[0010]

In order to achieve the above object, a vertical induction heating furnace according to the present invention has an induction heating coil on the outer periphery of a box-shaped furnace body having an opening for charging a slab at the bottom. In the vertical induction heating furnace that is arranged, an elevating wall that is vertically movable as a separate body from the furnace body and is made of a refractory heat insulating member that constitutes at least a part of the furnace top inner wall of the furnace body, Elevating wall driving means for vertically moving the elevating wall toward the upper end surface of the inserted slab in the width direction is provided.

[0011]

If the relative distance between the furnace top side upper end surface of the slab and the refractory heat insulating member forming the inner wall of the furnace body top is separated by a predetermined distance or more due to the dimension in the width direction of the slab loaded in the furnace, By driving the elevating wall drive means composed of a cylinder device or the like to lower the elevating wall forming part or the whole of the furnace top inner wall,
The elevating wall is brought close to or pressed against the upper end surface of the slab on the furnace top side.

By performing induction heating in this state, the area of the refractory heat insulating member that receives radiant heat from the upper end of the slab on the furnace top side is reduced, and thus the heat absorption to the fire resistant heat insulating member is reduced and the furnace top of the slab is reduced. The amount of heat radiated from the side edges is reduced.

[0013]

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 2 is arranged on the outer circumference of a side wall of a box-shaped furnace body 1. The lower part of the furnace body 1 is opened and a slab 3 is formed.
A support hearth 4 which forms the charging port 1a and on which the slab 3 is mounted is arranged below the charging port 1a so as to be able to move up and down. The hearth 4 is supported from below by a hearth elevating beam 5, and can be vertically reciprocated by an actuator (not shown).

A charging member sealing member 6 is extended upward to surround the upper part of the hearth 4 on the outer circumference of the upper part of the hearth 4
The upper end portion of the charging portion sealing member 6 can be charged into the concave portion 7 provided on the outer periphery of the lower end portion of the furnace body, and constitutes a charging portion sealing mechanism. A support rod 8 penetrates through the top part 1b of the furnace body 1 so as to be vertically movable, and the upper end part of the support rod 8 is connected to a cylinder device 10 for driving a support rod through a connecting member 9 to form the cylinder device. The support rod 8 moves up and down by 10. A plurality of the support rods 8 are arranged along the longitudinal direction of the furnace body 1.

Further, the inner wall portion of the top portion 1b of the furnace body 1 is vertically doubled, and the upper wall portion is integral with the main body of the furnace body 1, but the lower wall portion is the furnace body. An elevating wall 11 which is formed separately from the main body 1 and can be vertically moved up and down inside the furnace body 1.
Make up. The elevating wall 11 is divided by a plurality of support rods 9 penetrating the furnace body top portion 1b, and the outer periphery of each divided elevating wall 11 has a gap required for elevating the inner wall of the furnace body 1. is doing.

The respective elevating walls 11 correspond to the elevating rod 1
2, the lifting rod 12 penetrates the furnace body 1 top portion 1b so as to be vertically movable, and the upper end portion thereof is connected to a connecting member 13
And a driving member for driving the elevating wall, the elevating rod, the connecting member 13, and the elevating wall driving cylinder device 14 constitute an elevating wall driving device, and the elevating wall driving device is driven by the cylinder device 14. The wall 11 moves up and down. The elevating wall drive cylinder device 14 is fixed to the furnace body 1 by a supporting member (not shown).

As shown in FIG. 3, the elevating wall 11 is formed by stacking a plurality of ceramic fiber boards 11a, which are refractory heat insulating members, in the furnace width direction, that is, in the thickness direction of the slab 3, with its upper part facing downward. The through bolt 1 is inserted into the concave metal frame 11b, and the through bolt 1 is inserted in the above-mentioned overlapping direction (furnace width direction).
A plurality of ceramic fiber boards 11a are integrated and fixed to the metal frame 11b by being bolted through 1c. In addition, the lower end of the lifting rod 12 is fixed to the metal frame 11b.

In the vertical induction heating furnace having the above-mentioned structure, the slab 3 whose width direction is up and down is placed on the hearth 4, and the support rod 8 is lowered so that the lower end surface of the support rod 8 is slab 3. Is pressed against the upper end surface of the slab 3 and the slab 3 is clamped from above and below by the support rod 8 and the hearth 4. Then, while maintaining the above state, the hearth 4 is raised to load the slab 3 into the furnace body 1.

At this time, the upper end of the charging portion sealing member 6 provided in the hearth 4 is inserted into the concave portion 7 of the furnace body 1 so as to surround the charging port 1a which is the lower part of the furnace body 1. Is sealed so that the atmosphere in the furnace is kept constant. Here, the height at which the upper surface of the hearth 4 can be raised, that is, the height of the lower end surface of the slab 3 placed on the hearth 4 is determined by the positional relationship with the induction heating coil 2 and the charging member sealing member. Since it is determined in advance from the allowable stroke amount in the vertical direction of 6,
Normally, the height of the raised hearth 4 is set to a constant height.

Therefore, the distance between the upper end surface of the loaded slab 3 and the inner wall of the furnace top 1b located above the upper surface changes depending on the width of the slab 3. In this embodiment,
In order to reduce the above distance according to the width of the slab 3,
The elevating wall 11 is lowered by the elevating wall drive cylinder device 14, and the lower surface of the elevating wall 11 is brought close to or in contact with the upper end surface of the slab 3.

In the above-mentioned state, when a predetermined current is supplied to the induction heating coil 2, the induction current flows through the inserted slab 3 to generate heat and heat the slab 3. At this time,
Since the elevating wall 11 in the upper part of the furnace is lowered according to the width dimension of the slab 3 and the upper end surface in the width direction of the slab 3 and the elevating wall 11 are brought close to or in contact with each other, heat is applied to the upper end surface in the width direction of the slab 3. The area of the fireproof heat insulating member that exchanges
The heat radiation from the slab 3 is suppressed as compared with the conventional one, and uniform heating in the width direction of the slab 3 becomes possible.

The structure of the elevating wall 11 is the same as the slab 3
Since the metal frame 11b and other metal objects are not located on the lower side facing the upper end surface, heat removal from the slab 3 by the metal objects is suppressed, and heat radiation from the slab 3 and induction heating coils are suppressed. The induction heating from 2 suppresses the rise in temperature, reduces the occurrence of metal fatigue such as corrosion and wall thinning of the metal part, and reduces the risk of the lifting wall 11 falling off.

In order to confirm whether the uniform heat treatment of the slab 1 is actually improved, the case where the slab 3 is heated by the conventional induction heating furnace without the elevating wall 11 and the elevating wall 11 of this embodiment. When the temperature distribution along the longitudinal direction of the widthwise upper end face of the slab 3 was measured in the case where the slab 3 was heated in the induction heating furnace using, the results shown in FIG. 4 were obtained.

In FIG. 4, the dotted line shows the temperature distribution in the case of heating in the induction heating furnace according to this embodiment, and the alternate long and short dash line shows the temperature distribution in the case of heating in the conventional induction heating furnace. The solid line is measured on the surface of the central portion of the slab 1 in the width direction. As can be seen from this figure, the temperature of the upper end surface in the width direction of the slab 3 according to the present embodiment approaches the temperature of the central portion as compared with the conventional case, and the slab 3 is heated uniformly in the width direction. In addition, although there are several recessed portions in the temperature distribution in the figure, this is a portion that is in contact with the support rod 8 without vertically facing the elevating wall 11, and heat removal to the support rod 8, etc. The temperature has dropped by the amount.

In the above embodiment, the support rod 8 and the elevating wall 11 are individually moved up and down by the driving means such as the separate cylinder devices 10 and 14, but the invention is not limited to this, and the elevating wall 11 is not limited to this. May be supported by the support rod 8 and moved up and down together with the support rod 8.

[0026]

As described above, in the vertical induction heating furnace of the present invention, the amount of heat radiated from the upper end of the slab width direction, which is the object to be heated, is suppressed, and the temperature in the slab width direction is lower than that of the conventional one. The effect is that it can be heated uniformly.

[Brief description of drawings]

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

FIG. 2 is a cross-sectional side view in the width direction of FIG.

FIG. 3 is a side view showing a structure of an elevating wall.

FIG. 4 is a diagram showing a temperature distribution along a longitudinal direction of a widthwise upper end portion of a slab.

[Explanation of symbols]

 1 Furnace Body 2 Induction Heating Coil 3 Slab 8 Support Rod 11 Elevating Wall 12 Elevating Rod 13 Connecting Member 14 Elevating Wall Drive Cylinder Device

Claims (1)

[Claims] 1. A vertical induction heating furnace in which an induction heating coil is arranged on the outer periphery of a box-shaped furnace body having an opening for charging a slab at the bottom, and at least a part of the inner wall of the furnace top of the furnace body. And a rising / lowering wall which is made of a fireproof heat insulating member and which can be moved up and down as a separate body from the furnace body, and an ascending / descending wall drive for vertically moving the lifting wall toward the upper end surface in the width direction of the slab loaded in the furnace. A vertical induction heating furnace comprising: