JP2003279265A - Water-cooled panel for electric furnace - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To manufacture a water-cooled panel by cast steel. <P>SOLUTION: This water-cooled panel for an electric furnace is characterized by having the following structures: the water-cooled panel is a casting product made of cast steel; the outside of the water-cooled panel is a box shape; inside the water-cooled panel, a cooling water passage for passing cooling water is provided; outside the water-cooled panel and inside curved part, curvature of a radius of 15 mm or more is provided; and the thickness of the panel is 15 mm or less. The outside of the water-cooled panel is formed in a corrugated shape. The cooling water passage arranged in an inside end part of the water- cooled panel is formed so that the cross-sectional area of the passage becomes smaller than the other cooling water passage. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a water-cooled panel provided in a melting furnace for metallic materials. More specifically, the present invention relates to a water-cooled panel made of cast steel that is used by being attached to a furnace wall, a ceiling or the like of a melting furnace.

[0002]

2. Description of the Related Art In electric furnaces, so-called water-cooled panels such as cooling panels having a steel pipe structure, which is a pipe assembly, and cooling plates having a steel plate welded structure, which is called a can-making jacket type or box type are used. There is. FIG. 4 shows a schematic diagram of an example in which a water-cooled panel is used in an electric furnace. The water-cooled panel 53 has a molten steel 5 of the electric furnace 50 whose outer periphery is covered with a steel shell 54.
It is attached to the periphery of the bottom 51 of the furnace for holding 2. Among the water-cooled panels, the pipe assembly is excellent in water-cooling effect and has a long service life of several years to ten and several years.

FIG. 3 shows an example of a water-cooled panel on the ceiling of an electric furnace of a welded structure. 3A is a plan view of the water-cooled panel, and FIG. 3B is a front view thereof. In FIG. 3 (b), the lower side of the drawing is the surface in contact with the high temperature part of the furnace. The water cooling panel 40 shown in FIG. 3 is manufactured by welding the entire surface. Here, the cooling water 42 for cooling the water-cooled panel 40 flows in from the cooling water inlet 43, passes between the partition plate 41 provided as shown by the arrow and the side plate of the panel, and reaches the cooling water outlet 44. Head over.

[0004]

In the case of the pipe assembly described above, the construction and assembly of the U pipe portion are minute, so that it is time-consuming to manufacture and expensive equipment. Therefore, transformers are used in specific furnaces such as high-load furnaces and furnaces with high operating rates. By the way, the welded structure described above has the following problems.

The first problem is that there are welding defects during welding. The reason is that the water-cooled panel is complicated, so that the welding workability is poor and welding defects are likely to occur. In addition, the boundary line between the base material and the welded portion may be easily cracked. Furthermore, S specified in JIS G3101 that is usually used when manufacturing welded structures
The S400 material has C, Mn and C. E
Since the amount of (carbon equivalent) is not specified, it cannot be said that it is suitable for a material that is unlikely to crack.

The second problem is that the welded structure cannot have a curved welded portion. Therefore, the places where the thickness of the plate material of the water-cooled panel greatly changes, including the welded portion, remain as they are. In addition, the welded beat portion has a microscopic acute angle. Mechanical stress and thermal stress are concentrated in such places, which may cause cracking.

A third problem is that the water-cooled panel of the welded structure has, for example, SS40 specified in JIS G3101.
It means that a steel material having a thickness of 16 mm to 19 mm is used as 0 material. As described above, when a water-cooled panel is manufactured using a thick steel material, the surface portion is hard to be cooled due to the large thickness, and the surface temperature becomes relatively high.

Therefore, a temperature difference occurs between the high temperature surface on the outside of the water cooling panel and the cooling water contact surface on the inside of the water cooling panel, and the entire water cooling panel is deformed or cracks occur in the water cooling panel. Further, since the high temperature and the low temperature due to the operation are repeated, the steel material is repeatedly expanded and contracted, and cracks are likely to occur.

Each of the water-cooled panels of the pipe assembly and the welded structure has advantages and disadvantages. In particular, the water-cooled panel of the welded structure has a problem that its life is short. The present inventor, as a result of diligent examination of these problems, has found that the problem can be solved by manufacturing a water-cooled panel from cast steel.

[0010]

In order to solve the above-mentioned problems, a first aspect of the present invention is a water-cooled panel for an electric furnace, which has the following structure. (A) the water-cooled panel is a cast product made of cast steel, (b) the outer side of the water-cooled panel has a box shape, and the inner side of the water-cooled panel is provided with a cooling water passage for passing cooling water, (c) ) The outer and inner curved portions of the water-cooled panel have a radius of curvature of 15 mm or more, and (d) the thickness of the panel is 15 mm or less.

A second aspect of the present invention is the water-cooled panel for an electric furnace, wherein the outer side of the water-cooled panel is formed in a corrugated shape.

According to a third aspect of the present invention, the cooling water passage provided at the inner end of the water cooling panel is formed so that the cross sectional area of the passage is smaller than that of other cooling water passages. This is a water-cooled panel for an electric furnace.

A fourth aspect of the present invention is the water-cooling panel for an electric furnace, wherein the inside of the water-cooling panel is provided with irregularities in the cooling water passage on the side in contact with high temperature.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION FIG. 1 shows an embodiment of the present invention.
It demonstrates using (a) -FIG.1 (c). Figure 1 (a)
1 is a schematic view of a front view of a cast steel water-cooled panel according to the present invention.
FIG. 1 (b) is a schematic plan view. FIG. 1 (c) is a schematic side view.

In the present embodiment, the water cooling panel is a cast product made of cast steel, and the outer shape of the water cooling panel is a box shape.
Inside the water cooling panel, a cooling water flow path for passing cooling water is provided. All the outer and inner curved portions of the water cooling panel have a radius of curvature of 15 mm or more. The wall thickness of the water-cooled panel is 15 mm or less.

In the present embodiment, the water-cooled panel is a cast steel casting. Cast steel is, for example, JIS G5101, JIS
Those specified in G5102 can be used. In the present invention, low thermal conductivity, it is also possible to use a ductile cast iron having characteristics such as a low melting point, the water-cooled panel that is the object of the present invention, in order to obtain the characteristics described below, cast steel casting It is desirable to use it as a product.

In this embodiment, the cast steel is the same as the JI
In addition to those specified in SG5101, JISG5102, the content ratio of C is higher than that in SS400 specified in JISG3101, C.I. Steel with low E (carbon equivalent), that is,
It is desirable to use a material that does not easily break.

For example, JIS G 3101 rolled steel for general structure includes SS400 and SS490, which are used as chemical components (chemical component values are shown below by weight%).
P content is 0.050% or less, S content is 0.05
0% or less is shown.

In the present invention, in order to reduce the crack susceptibility, the C content is 0.05 to 0.20%, the Mn content is 0.50 to 1.00%, and the P content is 0. 025% or less, S content is 0.025% or less, C.I. E (carbon equivalent: C + Mn / 6 + Si / 24 + Ni / 40 + Cr / 5
It is desirable to use steel having a + Mo / 4 + V / 14) of 0.20 to 0.40%.

If the C content is less than 0.05%, the steel is apt to be deformed due to insufficient strength, and if the C content exceeds 2.0%, the susceptibility to cracking increases and cracking occurs. It will be easier. If the Mn content is less than 0.50%, the strength tends to be insufficient, resulting in deformation, and if the Mn content exceeds 1.00%, the cracking susceptibility increases and cracking easily occurs. If the P content exceeds 0.025%, cracks are likely to occur due to the formation of nonmetallic inclusions.

If the S content exceeds 0.025%, cracks are likely to occur due to the formation of nonmetallic inclusions. C. When E (carbon equivalent) is less than 0.20%,
Cracking is likely to occur due to insufficient strength, and if it exceeds 0.40%, cracking sensitivity increases and cracking tends to occur.

In the present embodiment, since the water-cooled panel is a cast steel product, for example, cast steel can be cast and integrally formed. Further, since it is a cast steel product, there is no welding site on the surface 5 exposed to the furnace. Therefore, it is possible to eliminate problems caused by welding work. Since it is a cast steel product, when damage (cracking, melting loss) occurs on the surface of the water-cooled panel during operation of the electric furnace or charging of the material into the electric furnace, the damaged portion can be easily repaired by welding. Therefore, it is not necessary to stop the operation for repair.

The surface 5 of the water-cooled panel that is normally exposed to the furnace
5 to 10 m of slag scattered from the surface of the molten metal
Adhere to a thickness of m. By the slag adhering to the water-cooled panel, it is possible to mitigate the thermal shock caused by the sudden rise in temperature when the molten metal splashes again and adheres to the water-cooled panel.
Further, the slag attached to the water-cooled panel also has a heat insulating effect of protecting the water-cooled panel from the high temperature atmosphere in the furnace.

Therefore, in this embodiment, the surface is formed in a corrugated shape so that the attached slag is unlikely to peel off. In order to prevent the slag from peeling off from the water-cooled panel, the surface 5 of the water-cooled panel exposed to the furnace is formed in a corrugated shape as in the present embodiment, a dimple of any shape is provided, or an arbitrary shape. The surface shape may be freely formed such as by providing a hump-shaped projection.

In this embodiment, since sand is used for the mold,
The outer surface of the water-cooled panel can be satin finished. The surface 5 exposed to the furnace can be formed into a suitable matte surface by appropriately selecting the grain size of sand, so that the slag can be more difficult to peel off.

In this embodiment, a water-cooled panel having a complicated shape can be manufactured by casting. This will be described with reference to FIG. For example, in order to give the water-cooling panel outer corner portion 6 a curve, it is desirable that the water-cooling panel be formed in an arc shape or a curved shape. The curved surface shape means an arc having no protrusion, such as an elliptic arc shape. By forming the corners in the shape of an arc or a curved surface, it is possible to mitigate the concentration of thermal stress that tends to occur in the acute corners and the protrusions, and to suppress the occurrence of cracks and the like.

For example, the outer corner portion 6 of the water cooling panel can be formed in an arc shape. In that case, if the radius of the arc is represented by R (unit: mm), the radius can be selected to any value. In the present embodiment, it is desirable that R = 15 mm or more. This is because if R = 15 mm or less, stress concentrates and cracks easily occur.

In this embodiment, the surface 5 exposed in the furnace
The temperature difference on the side was reduced. That is, in order to increase the cooling efficiency by increasing the flow velocity of the cooling water in the water cooling panel,
Compared to the conventional welded structure, the height 11 and the width 12 of the cooling water flow passage 2 are reduced, and the cross-sectional area of the cooling water flow passage 2 is reduced.

By narrowing the cross-sectional area, the cooling water flow path 2
The cooling efficiency of the water-cooled panel can be increased by increasing the flow velocity in the inside. Moreover, since the heat transfer is increased and the temperature difference between the outer side surface and the inner side surface of the water-cooled panel is reduced by narrowing the cross-sectional area, it is possible to reduce the possibility of cracks in the water-cooled panel.

Regarding the cooling water flow passage provided inside the water cooling panel, the cooling water flow passage end 16 at the panel end is
In order to increase the flow rate of the cooling water and increase the cooling efficiency, it was formed so that the cross-sectional area of the flow channel was smaller than that of other cooling water flow channels. In particular, the cooling water flow passage arranged on the side closer to the molten metal in the electric furnace has a smaller cross-sectional area than the other cooling water flow passages so as to increase the cooling water flow rate and increase the cooling efficiency. It is desirable to form it. The rate of reducing the cross-sectional area varies depending on factors such as the operating conditions of the furnace and the size of the panel, and thus can be appropriately selected during manufacturing.

Further, the cooling water flow path 2 on the surface 5 exposed to the inside of the furnace is provided with the cooling flow path uneven portion 14. By providing the cooling water flow passage concave-convex portion 14, the contact area between the steel material of the cooling water flow passage 2 and the cooling water is expanded, the cooling efficiency can be further improved, and the possibility of cracking in the water cooling panel can be reduced. You can

In the present embodiment, it is desirable that the cooling water flow path corner portion 15 inside the water cooling panel 1 is formed in an arc shape or a curved shape so as to be curved. The curved surface shape means an arc having no protrusion, such as an elliptic arc shape. By forming the corners in an arc or curved shape,
Since the resistance when passing through the cooling water passage 2 is reduced and the turbulent flow generation at the corner portion 15 of the cooling water passage can be reduced, the pressure loss can be reduced.

For example, the corner portion 15 of the cooling water passage can be formed in an arc shape. In that case, if the radius of the arc is represented by R (unit: mm), the radius can be selected to any value. In the present embodiment, it is desirable that R = 15 mm or more.

In this embodiment, the thickness of the cooling panel is 2
1. For example, the wall thickness including the cooling water flow path partition 13 is 15 m
The thickness was set to m or less so that the temperature difference inside and outside the cooling panel was reduced. As a result, the temperature rise on the surface of the water-cooled panel is suppressed, expansion and contraction on the heat-receiving side of the water-cooled panel is reduced, and cracks are reduced. The thickness of the water-cooled panel is 10
15 mm is desirable. More preferably 10 to 12 mm
Is desirable, but it is possible to make it thinner.

[0035]

EXAMPLES Examples of the present invention are shown below. The water-cooled panel shown in FIG. 1 was manufactured as follows. The size of the water-cooled panel is approximately 1 m in length and 1 m in width.

The shape and dimensions of the cooling water passage are almost as shown in FIG. Welded structure, width 150 mm x length 7
In the present invention, an 8 mm cooling water flow path has a width of 97.5 mm ×
The cooling water flow path was 60 mm in length. Therefore, the cross-sectional area is
It was almost halved. In the present invention, the width is 90 mm
× Height can be 60 mm. The R dimension of the outer corner of the cooling panel shown in FIG. 2 was set to 45 mm. The other R parts are
R = 15 mm or more. The wall thickness was 15 mm.

First, a mold was produced by adding carbonic acid-curable resin as a sintering material to high alumina cera beads and by a carbon dioxide method. The core is a core metal (diameter is 12
mm steel wire) was used. The composition of the components melted in the high-frequency electric furnace in the mold has a C content of 0.12%, a Mn content of 0.65%, a Si content of 0.35%, and a P content of 0.020. %, S content is 0.005%, and C.I.
Molten steel with an E (carbon equivalent) of 0.32% and a casting temperature of 1
Casting was performed at 530 ° C. It should be noted that the sprue was provided at four places so as not to cause a defective pouring of the melt.

After casting, it was allowed to cool and the cast product was taken out of the mold. The mold could be easily broken. Further, the core sand and the core metal in the hollow portion were also free from seizure and could be taken out easily and in a short time. After that, the usual water blasting treatment was performed to obtain a water-cooled panel.

[0039]

EFFECTS OF THE INVENTION By manufacturing the water-cooled panel from cast steel, the welding defects at the time of welding work are eliminated, the stress is concentrated by processing into a curved surface, and the cause of cracking is reduced. In addition, the wall thickness has been reduced to reduce deformation and cracking of the entire water-cooled panel. Therefore, the cast steel water-cooled panel of the present invention is superior in life and cost as compared with the water-cooled panel having the steel pipe structure and the steel plate welded structure.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a water-cooled panel of the present embodiment.

FIG. 2 is a partially enlarged schematic view of the water cooling panel of the present embodiment.

FIG. 3 is an example of a water-cooled panel having a steel plate welded structure.

FIG. 4 is an example of an electric furnace provided with a water cooling panel.

[Explanation of symbols]

1 water cooling panel 2 Cooling water flow path 3 Cooling water inlet 4 Cooling water outlet 5 Surface exposed to the furnace 6 Water cooling panel outer corner 11 Cooling water flow path height 12 Cooling water channel width 13 Cooling water flow path partition 14 Cooling channel irregularities 15 Cooling water channel corners 16 Cooling water flow path end 21 Cooling panel thickness 40 water cooling panel 41 partition 42 Cooling water 43 Cooling water inlet 44 Cooling water outlet 50 electric furnace 51 hearth 52 Molten Steel 53 Water cooling panel 54 iron skin

[Procedure amendment]

[Submission date] April 3, 2002 (2002.4.3)

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0020

[Correction method] Change

[Correction content]

If the C content is less than 0.05%, the strength tends to be insufficient so that the steel is likely to be deformed.
If it exceeds 0.20% , the cracking susceptibility increases and cracking easily occurs. If the Mn content is less than 0.50%, the strength tends to be insufficient, resulting in deformation, and if the Mn content exceeds 1.00%, the cracking susceptibility increases and cracking easily occurs. 0.025% P content
If it exceeds, cracks are likely to occur due to the formation of non-metallic inclusions.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Toru Suzuki             2-1, Shiraishi-cho, Kawasaki-ku, Kawasaki-shi, Kanagawa             Inside Hon Foundry Co., Ltd. (72) Inventor Shigeki Akimoto             2-1, Shiraishi-cho, Kawasaki-ku, Kawasaki-shi, Kanagawa             Inside Hon Foundry Co., Ltd. F-term (reference) 4K051 AA05 AB01 AB03 HA03

Claims (4)

[Claims] 1. A water-cooled panel for an electric furnace having the following structure. (A) The water-cooled panel is a cast product made of cast steel, and (b)
The outer side of the water cooling panel has a box shape, and the inner side of the water cooling panel is provided with a cooling water flow path for passing cooling water. (C) A radius of 15 is provided between the outer and inner curved portions of the water cooling panel.
With a curvature of mm or more, (d) the thickness of the panel is 15 m
m or less. 2. The water-cooled panel for an electric furnace according to claim 1, wherein an outer side of the water-cooled panel is formed in a corrugated shape. 3. The cooling water passage provided at the inner end of the water cooling panel is formed so that the cross-sectional area of the passage is smaller than that of other cooling water passages. The water-cooled panel for an electric furnace according to 1 or 2. 4. The water cooling for an electric furnace according to claim 1, wherein an inner surface of the water cooling panel is provided with irregularities in a cooling water flow path on a side in contact with a high temperature. panel.