JP2021031752A - Metal body heating furnace for heating metal body - Google Patents

Abstract

To provide a metal body heating furnace in which a displacement of a refractory frame and an occurrence of a flaw on a lower surface of a metal body can be prevented when heating the metal body.SOLUTION: A metal body heating furnace includes: a cylindrical or spherical metal body placing refractory on which a metal body is placed; and a rotation-holding refractory having a recess for rotatably holding the metal body placing refractory. A metal body is heated by using the metal body heating furnace which has an Al2O3-based coating layer or Al2O3-SiO2-based coating layer on a surface of the metal body placing refractory to which the metal body contacts.SELECTED DRAWING: Figure 1

Description

The present invention relates to a metal body heating furnace for raising the temperature (hereinafter, referred to as temperature rise) of a metal object (hereinafter, referred to as a metal body) such as a steel material or a casting.

In the present invention, the temperature rise is a temperature rise for heating the metal body prior to processing the metal body at a high temperature (for example, hot rolling), or a heat treatment (for example, quenching, tempering, annealing) on the metal body. It means various temperature rises performed in the metal body manufacturing process, such as temperature rise for applying heat treatment.

In a metal body heating furnace used to raise the temperature of a metal body in a series of manufacturing processes of a metal body, a plurality of refractory pedestals are arranged on a hearth, and the metal body is placed on the refractory pedestal. It is configured to raise the temperature of the metal body by placing it and holding it in the furnace. FIG. 2 is a cross-sectional view schematically showing an example of a conventional refractory frame.

As shown in FIG. 2, in the refractory frame 1 of the metal body heating furnace that has been conventionally used, the refractory material for the column, which is the column of the refractory frame 1, is arranged on the hearth 4. FIG. 2A shows an example in which the refractory material for the strut is divided into upper and lower parts (that is, the upper refractory material for the strut 3a and the lower refractory material for the strut 3b) to form the refractory frame 1, and FIG. This is an example in which the refractory material 3 for a single strut, which is specifically molded, is used.

An upper refractory 2 is arranged at the upper end of the prop refractory 3a (see FIG. 2A) or the strut refractory 3 (see FIG. 2B). The central portion of the upper end refractory 2 is projected in a convex shape, and the metal body (not shown) in the furnace is placed on the convex portion of the upper end refractory 2. Therefore, the lower surface of the metal body and the convex portion of the upper end refractory 2 come into contact with each other.

Then, the metal body expands as the temperature rises in the metal body heating furnace, and friction with the convex portion of the upper end refractory 2 generates a frictional force in the horizontal direction. When the metal body heating furnace is operated for a long period of time, there arises a problem that the refractory gantry 1 in the furnace gradually moves due to the frictional force and deviates from the position arranged at the start of the operation.

When the metal body is charged before the temperature rises, or when the metal body is carried out after the temperature rise is completed, a device that lifts the metal body from below (so-called extractor) is used. If the position of 1 is deviated, the extractor cannot enter between the refractory pedestals 1 adjacent to each other, causing the operation of the metal body heating furnace to be stopped.

After that, using a hook rod or the like, the refractory pedestal 1 can be returned to the normal position, or the refractory pedestal 1 can be collapsed and discharged to the outside of the furnace so that the extractor can enter. It is possible to resume the operation after the operation is completed, but it is inevitable that the operating rate of the metal heating furnace will decrease. Moreover, since the work is performed in a high temperature environment, a large cost is required for measures for the safety of workers.

Further, when the displaced refractory frame 1 is disintegrated and discharged to the outside of the furnace, the load of the metal body on the sound (that is, in the normal position) refractory frame 1 increases during the work. Therefore, the frictional force due to the expansion of the metal body also increases. As a result, the position of the sound refractory pedestal 1 is likely to shift. Further, there is a problem that a flaw (for example, a scratch) is generated on the lower surface of the metal body in contact with the convex portion of the upper end refractory 2. In this way, when the number of misaligned refractory pedestals 1 increases or defects occur on the lower surface of the metal body, it is necessary to extinguish the metal body heating furnace and perform large-scale repair work. is there.

If the refractory pedestal 1 is firmly fixed on the hearth 4, it is possible to prevent the refractory pedestal 1 from being displaced. However, the frequency of frictional flaws caused by the expansion of the metal body increases significantly on the lower surface of the metal body.

Therefore, various techniques for preventing the displacement of the refractory frame 1 and preventing the occurrence of flaws on the lower surface of the metal body when the temperature of the metal body is raised by using the metal body heating furnace have been studied. ing.

For example, in Patent Document 1, a pedestal (corresponding to a refractory pedestal of the present invention) is constructed by simply contacting bricks or bricks with a hearth without sticking them (referred to as non-sticking free contact). The batch furnace is disclosed. Although this technique can prevent scratches from occurring on the lower surface of the metal body, the pedestal is displaced due to the frictional force caused by the expansion of the metal body acting on the pedestal. Furthermore, if the metal body expands significantly, the pedestal may collapse.

Patent Document 2 discloses a box-type furnace in which a sliding layer is provided on a contact surface between bricks. By applying this technique to provide a slip layer between the hearth and the refractory pedestal, it is possible to prevent scratches on the underside of the metal body, but friction due to the expansion of the metal body. The force acts on the refractory pedestal, causing the pedestal to shift. Moreover, there is a risk that the misalignment will increase due to the provision of the slip layer.

Japanese Unexamined Patent Publication No. 9-49014 Special Fair 5-45644 Gazette

INDUSTRIAL APPLICABILITY The present invention can solve the problems of the prior art, prevent the position of the refractory pedestal from shifting when the temperature of the metal body is raised, and prevent scratches from occurring on the lower surface of the metal body. It is an object of the present invention to provide a possible metal body heating furnace.

The present inventor pays attention to the shape of the portion where the upper end refractory material constituting the refractory frame comes into contact with the lower surface of the metal body, and achieves both prevention of misalignment of the refractory frame and prevention of flaws in the metal body. We examined the technology for this. Then, the above problem can be solved by arranging a columnar or spherical refractory for mounting the metal body on a portion in contact with the lower surface of the metal body and freely rotating the refractory for mounting the metal body. I found it. In other words, since the fire-resistant material for mounting the metal body rotates following the expansion of the metal body, the frictional force caused by the expansion of the metal body can be reduced, and as a result, the displacement of the fire-resistant material frame can be prevented. Moreover, it is possible to prevent scratches from occurring on the lower surface of the metal body.

Furthermore, by forming a coating layer of oxide (for example, Al ₂ O ₃ , Al ₂ O _3- SiO ₂ etc.) on the surface of the refractory for mounting the metal body, the refractory for mounting the metal body and the metal body can be formed. It was found that sticking can be prevented.

The present invention has been made based on such findings.
That is, the present invention is a metal body heating furnace that heats or heat-treats by raising the temperature of the metal body, and is a columnar or spherical refractory for mounting the metal body on which the metal body is placed, and a metal body mounting. _{An Al 2} O ₃ coating layer or an Al 2 O 3 coating layer on the surface of a metal body mounting refractory that has a rotation holding refractory with recesses for rotatably holding the mounting refractory and is in contact with the metal body. It is a metal body heating furnace equipped with an Al ₂ O _3- SiO _{2 coating layer.}

According to the present invention, when the temperature of the metal body is raised, the operating rate of the metal body heating furnace is improved by preventing the displacement of the refractory frame, and the lower surface of the metal body is flawed. By preventing this, it is possible to improve the yield of the metal body, which is extremely effective in the industry.

If the present invention is applied to a type of heating furnace (so-called batch furnace) in which a metal body is charged and carried out using an extractor, the operating rate of the metal body heating furnace can be improved and the yield of the metal body can be improved. It is preferable because the effect becomes remarkable. However, it can also be applied to a type of heating furnace (for example, a walking beam furnace) in which a metal body is continuously charged and carried out.

It is sectional drawing which shows typically the example of the refractory pedestal which concerns on this invention. It is sectional drawing which shows typically the example of the conventional refractory frame. It is a perspective view which shows typically the example of charging or extracting a metal body in a simplified manner.

FIG. 1 is a cross-sectional view schematically showing an example of a refractory frame 1 according to the present invention. In the present invention, a refractory material for a column serving as a column of the refractory frame 1 is arranged on the hearth 4. Will be done. FIG. 1 (a) shows an example in which the refractory material for the strut is divided into upper and lower parts (that is, the upper refractory material for the strut 3a and the lower refractory material for the strut 3b) to form the refractory frame 1, and FIG. This is an example in which the refractory pedestal 1 is constructed by using the refractory material 3 for a single strut that is specifically molded.

A rotation-holding refractory 9 is arranged at the upper end of the column upper refractory 3a (see FIG. 1 (a)) or the column refractory 3 (see FIG. 1 (b)). The central portion of the rotation-holding refractory 9 is recessed in a concave shape, and the columnar or spherical metal body mounting refractory 8 is housed in the recess so that the rotation-holding refractory 9 does not fall off. The refractory material 8 for mounting the metal body rotates freely in the recess.

The material of the refractory material 8 for mounting the metal body is not particularly limited. For example, refractory materials of conventionally known materials such as refractory bricks containing SiC as a main component, silica stone bricks containing _{SiO 2 as a main component, and high alumina bricks containing Al 2} O _{3 as a main component are used.} The diameter of the refractory material 8 for mounting a metal body is preferably in the range of 100 to 200 mm in either a columnar shape or a spherical shape. If the diameter of the refractory material 8 for mounting the metal body is less than 100 mm, the refractory material 8 for mounting the metal body is likely to be damaged when the metal body is mounted as described later. When the diameter of the refractory material 8 for mounting the metal body exceeds 200 mm, the refractory material 8 for mounting the metal body tends to fall off from the refractory material 9 for holding the rotation when the refractory material 8 for mounting the metal body rotates due to the expansion of the metal body as described later. ..

A coating layer is formed on the surface of the refractory material 8 for mounting a metal body _{with a coating material containing Al 2} O _{3 as a main component.} The coating layer is _{a mixture of Al 2} O ₃ and a solvent sprayed to make the film thickness uniform, and then baked to firmly fix it (hereinafter referred to as Al ₂ O ₃ coating layer), or A mixture of a compound of Al ₂ O ₃ and SiO ₂ and a solvent is sprayed to make the film thickness uniform, and then baked to firmly fix it (hereinafter referred to as Al ₂ O _3- SiO ₂ coating layer). ).

_{By forming an Al 2} O ₃ system coating layer or an Al ₂ O ₃ −SiO ₂ system coating layer on the surface of the refractory material 8 for mounting a metal body, the metal body charged into the metal body heating furnace ( (Not shown) and the refractory material 8 for mounting the metal body can be prevented from sticking, so that the metal body heating furnace can be operated stably for a long period of time.

The cross-sectional shape of the concave portion of the refractory material 9 for holding rotation is not particularly limited, but the cross-sectional shape of the deepest portion (hereinafter referred to as the bottom portion) is preferably U-shaped or V-shaped. When the bottom of the recess has a U-shape, the inner diameter of the arc-shaped bottom and the diameter of the refractory for mounting the metal body 8 are made the same, so that the metal is mounted in the recess of the refractory for holding rotation 9. It is preferable because the refractory material 8 for placement rotates stably. When the bottom of the recess has a V shape, the angle of the wedge-shaped bottom is preferably in the range of 70 to 120 °. If the angle is less than 70 °, the diameter of the refractory material 8 for mounting the metal body that can be stored in the recess becomes small, so that the refractory material 8 for mounting the metal body is damaged when the metal body is mounted as described later. It will be easier. When the angle exceeds 120 °, when the refractory material 8 for mounting the metal body rotates due to the expansion of the metal body as described later, it easily falls off from the refractory material 9 for holding the rotation.

The material of the refractory material 9 for holding rotation is not particularly limited. For example, refractory materials of conventionally known materials such as refractory bricks containing SiC as a main component, silica stone bricks containing _{SiO 2 as a main component, and high alumina bricks containing Al 2} O _{3 as a main component are used.} However, it is preferable to use the same material as the refractory material 8 for mounting on a metal body. If the materials of the refractory for rotation holding 9 and the refractory for mounting the metal body 8 are different, one of the refractory for rotation holding 9 and the refractory for mounting the metal body 8 (that is, the material having low high temperature strength) is used. The refractory material) is significantly worn, and the durability of the refractory material frame 1 is impaired.

Then, as shown in FIG. 3, when the refractory pedestals 1 are arranged so as to form a plurality of rows and the metal body is placed on the refractory pedestal 1, the lower surface of the metal body is fireproof for mounting the metal body. Contact object 8. Then, when the metal body expands due to the temperature rise, the refractory material 8 for mounting the metal body rotates in the recess of the refractory material 9 for holding rotation due to friction with the lower surface of the metal body. As a result, the frictional force generated due to the expansion of the metal body is absorbed by the rotation of the refractory object 8 for mounting the metal body, so that the position of the refractory frame 1 can be prevented from shifting, and the metal body can be prevented from shifting. It is possible to prevent scratches (for example, rubbing scratches, etc.) from occurring on the lower surface of the surface.

Therefore, according to the present invention, the extractor 7 can be operated stably even if the metal body heating furnace is continuously operated for a long period of time, and by extension, the metal body can be smoothly loaded and unloaded. .. Moreover, the batch furnace as the metal body heating furnace can be operated without causing defects on the lower surface of the metal body.

When a walking beam furnace is used as the metal body heating furnace, if the metal body mounting refractory 8 and the rotation holding refractory 9 according to the present invention are arranged in the fixed beam and the moving beam, It is possible to prevent the misalignment of each beam. That is, since the interference between the fixed beam and the moving beam can be prevented, the metal body can be smoothly charged into the furnace, moved in the furnace, and carried out from the furnace. Moreover, in the walking beam furnace, loading, moving, and unloading can be performed without causing scratches on the lower surface of the metal body.

As shown in FIG. 1A, a lower refractory for columns 3b and an upper refractory for columns 3a are arranged on the hearth 4, and a refractory for holding rotation 9 is arranged at the upper end of the upper refractory for columns 3a. Further, a columnar refractory for mounting a metal body 8 (diameter 119 mm, length 295 mm) was housed in a recess of the refractory for holding rotation 9 to form a refractory stand 1. The refractory material 8 for mounting the metal body and the refractory material 9 for holding the rotation used the same components (SiC: 78% by mass, Si ₃ N ₄ : 16% by mass, SiO ₂ : 5% by mass).

For the surface of the refractory material 8 for mounting a metal body, _{a slurry-like suspension was prepared by mixing Al 2} O ₃ with water, a small amount of a binder, and a dispersant. This suspension was sprayed to form a film and then baked to form an Al ₂ O ₃ coating layer with a thickness of 50 μm.

Using a metal body heating furnace 6 (so-called batch furnace) in which such refractory pedestals 1 are arranged in a plurality of rows, the operation of raising the temperature of the steel plate to 600 to 1100 ° C. is continued for 3 months. I did it. The bottom of the recess of the refractory for holding rotation 9 has a U-shape having an arc shape with an inner diameter of 119 mm. This is referred to as Invention Example 1. The steel plate was loaded and unloaded using the extractor 7 (see FIG. 3).

Next, as shown in FIG. 1 (b), the refractory for columns 3 is arranged on the hearth 4, the refractory for rotation holding 9 is arranged at the upper end of the refractory for columns 3, and further rotation holding. The refractory frame 1 was constructed by accommodating the refractory 8 (diameter 119 mm, length 295 mm) for mounting a cylindrical metal body in the recess of the refractory material 9. The refractory material 8 for mounting the metal body and the refractory material 9 for holding the rotation used the same components (SiC: 78% by mass, Si ₃ N ₄ : 16% by mass, SiO ₂ : 5% by mass).

The surface of the metal body mounting refractory 8, Al ₂ O ₃ and compound _{(3Al 2 O 3 · 2SiO 2} ) and water and a small amount of the mixed slurry of suspension dispersant and a binder and SiO ₂ Was produced. This suspension was sprayed to form a film and then baked to form an Al ₂ O _3- SiO ₂ coating layer with a thickness of 50 μm.

Using a batch furnace in which the refractory pedestals 1 were arranged in a plurality of rows, the operation of raising the temperature of the steel plate to 600 to 1100 ° C. was carried out continuously for three months. The bottom of the recess of the refractory for holding rotation 9 has a V shape with an angle of 90 °. This is referred to as Invention Example 2. The steel plate was loaded and unloaded using the extractor 7.

When the inside of the batch furnace was inspected after the operation for three months in this way, no misalignment of the refractory pedestal was observed in any of Invention Examples 1 and 2. Therefore, the extractor could be operated smoothly for 3 months. Further, in both Invention Examples 1 and 2, no scratches due to friction with the refractory for mounting the metal body occurred on the lower surface of the steel material whose temperature was raised during the three-month period in which the batch furnace was operated.

1 Refractory pedestal 2 Top refractory 3 Strut refractory
3a Upper refractory for stanchions
3b Lower refractory for columns 4 Hearth 5 Hearth 6 Metal heating furnace 7 Extractor 8 Refractory for mounting metal 9 9 Refractory for holding rotation

Claims (1)

A metal body heating furnace that heats or heat-treats by raising the temperature of the metal body, and is a columnar or spherical refractory for mounting the metal body on which the metal body is placed, and a refractory for mounting the metal body. The surface of the refractory for mounting the metal body, which has a refractory for holding the rotation and has a recess for holding the object rotatably, is an Al ₂ O ₃ coating layer or Al. A metal body heating furnace characterized by having a ₂ O _3- SiO _{2 coating layer.}

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