JP2000008107A - Small bell and small bell cup in furnace top charging device of blast furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small bell and a small bell cup whose wearing losses are reduced on respective seat surfaces of their lower parts in a furnace top charging device of a blast furnace and also, which can be reused by repairing even at the time of reaching the worn limit. SOLUTION: In the small bell lower part 2 and the small bell cup lower part, the bodies of the lower parts are made of steel, and firstly, in order to form a cladded layer 6 by welding on the surface corresponding to each seat surface, a preparatory shaving is executed. Successively, a hardening and cladding by welding, with which carbide is dispersed in the fused and deposited metal and the deposited metal has at least 800 Vickers hardness, is applied. Further, the finishing work of the seat surface is executed and, thereafter, a sealing treatment to penetrate into welding cracks developed on the seat surface and fill the gaps, is applied.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a small bell and a small bell cup for a blast furnace top charging apparatus and a method for repairing the small bell.

[0002]

2. Description of the Related Art FIG. 5 shows an outline of a small bell and a small bell cup used as a charging device for a blast furnace in an ironworks. 1 is the upper part of the divided small bell, 2 is the lower part of the small bell, 3 is the upper part of the small bell cup, and 4 is the lower part of the small bell cup. The ironmaking raw material 12 stays in the space formed by these four parts. And, when appropriate, lower the small bells 1 and 2 down
The ironmaking raw material is dropped and transferred to a large bell (not shown).

[0003] Generally, the raw material for ironmaking is hard particles or lump such as iron ore and coke. When the raw material for ironmaking falls down and moves to the large bell by the vertical movement of the small bells 1 and 2, the raw material for ironmaking is small. The seat surface of the bell lower portion 2 and the seat surface of the lower portion of the small bell cup which repeatedly contact and separate from the seat surface are worn and depleted. For this reason, in the conventional small bell lower part 2 and the small bell cup lower part 4, in order to have abrasion resistance, a high chromium cast iron material is adopted and formed by casting.
The sheet surface has been manufactured by performing finishing processing by mechanical cutting.

However, in the manufacturing method by casting,
The maximum carbon content of high chromium cast iron is 3.5%, which is the limit of casting without cracking.
For this reason, the amount of chromium carbides required for improving the wear resistance was suppressed, and there was a limit in improving the wear resistance. In addition, in the heat treatment process after casting, since the cooling rate passes through the slow cooling rate, it is not possible to obtain fine carbide precipitation effective for improving abrasion resistance, resulting in coarse carbide precipitation. was there.

[0005] In addition, since the lower part of the small bell and the lower part of the small bell cup are integrally cast, each sheet surface is partially worn and degraded, and the performance of sealing the pressure inside the blast furnace is reduced. When the limit is reached, it must be replaced with a new one, and a part of the high chromium cast iron which is expensive due to abrasion loss of a part is discarded, so that there is a problem that it becomes a great burden economically.

[0006]

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and it is intended to reduce the wear loss of each of the seat surfaces at the lower part of the small bell and the lower part of the small bell cup and to reduce the wear limit. It is an object of the present invention to provide a small bell and a small bell cup which can be reused by repair even when they reach.

[0007]

The gist of the present invention for solving the above problems is as follows. (1) A small bell and a small blast furnace top charging device for holding a raw material for ironmaking in a space formed by a small bell and a small bell cup, and lowering the small bell appropriately to transfer the raw material for ironmaking downward. In the bell cup, the hard metal overlay welding is performed so that the deposited metal has a hardness of at least 800 or more in Vickers hardness on the lower surface of the steel bell and the lower sheet surface of the small bell cup. A small bell and a small bell cup, characterized by having a ground surface ground. (2) In the small bell and the small bell cup of the above (1), the deposited metal layer weld-welded to the uppermost layer of the surface serving as each sheet surface has a Vickers hardness of 350 to 700, and A small bell and a small bell cup having a build-up thickness of at least 3 mm or more. (3) In the small bell and the small bell cup of the above (1), after the overlay welding, each sheet surface is finished by grinding or mechanical cutting with a grindstone, and then the surface is subjected to the operating temperature of the small bell. A small bell and a small bell cup which have been subjected to a sealing treatment for penetrating a welding crack on a surface generated during hardfacing welding and filling a gap with a durable sealing treatment agent. (4) The small bell and the small bell of the blast furnace top charging device for holding the raw material for iron in the space formed by the small bell and the small bell cup, lowering the small bell as appropriate, and transferring the raw material for iron downward. In the method of repairing a small bell cup, when repairing a sheet surface which has reached a wear limit due to use, the deposited metal has a hardness of at least 800 or more in terms of Vickers hardness on each of the sheet surfaces under the small bell and the small bell cup. Repairing a small bell and a small bell cup of a blast furnace top charging device, characterized in that hardfacing welding is carried out so as to have, and then the hardfacing welded surface is ground or machine-cut and regenerated and repaired. .

[0008] More specifically, for the lower part of the small bell and the lower part of the small bell cup, which were conventionally cast products of high chromium cast iron, the main body is made of steel with good weldability, and the sheet surface which requires wear resistance is used. Is to disperse a large amount of fine carbides uniformly in a deposited metal by overlay welding of a welding material containing carbon exceeding a carbon content of 3.5%, which is a production limit by casting, and at least Hv 800 or more. By providing a hardfacing welded layer having hardness and then finishing by grinding or mechanical cutting using a grindstone, wear resistance is remarkably improved. In addition, when the wear limit is reached as the product is used, hard overlay welding with an Hv of 800 or more is performed again and finish processing is performed to provide a reusable small bell lower portion and a bell cup lower portion. If the hardness of the deposited metal is less than Hv800, the wear resistance is almost equal to that of a conventional high chromium cast iron casting, and it is difficult to expect a dramatic improvement.

In the overlay welding of the above (1), in the uppermost layer, that is, the final layer of the overlay welding, a welding material whose composition is designed so that the hardness of the deposited metal is from Hv350 to Hv700 is at least 3 mm or more. By performing the build-up welding at a thickness of, the finishing process can be easily performed by a general mechanical cutting process without depending on a complicated grinding process using a grindstone. The reason for changing from Hv350 to 700 is that if it is less than Hv350, the abrasion resistance decreases, the initial wear becomes remarkable, and the wear loss is accelerated. On the other hand, if Hv 700 or more, it is too hard and the difficulty of the mechanical cutting becomes extremely high. In addition, the reason why the thickness of the uppermost layer is set to at least 3 mm is that when the thickness is less than 3 mm, the main overlay has a hardness of Hv 800 or more due to component dilution due to penetration during welding of the uppermost layer. This is because a mixture with a metal component occurs, and even when a welding material having a hardness of Hv 350 is used, it may exceed Hv 700, which makes mechanical cutting extremely difficult.

Further, as the sealing agent capable of withstanding the environment of about 150 ° C., which is the operating temperature of the small bell, after the grinding or mechanical cutting described in the above (1) and (2), for example, Al-based or Using a Si-Al-based sealing material or a ceramics-based adhesive, by applying a sealing treatment to weld cracks inevitably generated in hardfacing welding, the airtightness of the sheet surface is improved, and the blast furnace The pressure inside the furnace can be reliably sealed.

[0011]

Embodiments of the present invention will be described below in detail. FIG. 1 shows an embodiment in which a lower part of a small bell is manufactured according to the present invention with respect to a small bell of a vertical split type. In this case, the structure of the small bell is a skirt-shaped small bell lower part 2.
Are assembled and fixed to the small bell upper part 1 made of cast steel by a plurality of bolts and nuts 5. Usually, a replaceable liner is attached to the small bell upper part 1 as a wear resistance measure, and as a wear resistance measure to the small bell lower part 2 having a sealing function, this is made by casting a high chromium cast iron. Supported. In the embodiment of the present invention, the small bell lower portion 2 was first cast with a cast steel material SCW450, and then the sheet surface portion 6 was machined down and then hardfacing welded. Regarding the thickness of the build-up welding, a depth 25 is required for the portion b of the sheet surface 6 where the wear loss is most severe.
Undercutting processing was performed on the mm and a portions at a depth of 20 mm and further on the c portion at a depth of 10 mm, respectively, to provide a build-up layer as indicated by the hatched portion 6.

In this embodiment, the small bell is of a vertical split type, and for overlay welding, the small bell lower part 2 is mounted on a positioner and rotated, and a submerged arc automatic welding method is employed as a welding method. Table 1 shows the build-up welding conditions.

[0013]

[Table 1]

Prior to the present embodiment, the wear resistance of the applied welding material was evaluated. As a method for evaluating the wear resistance of the material, a rubber wheel wear test method shown in FIG. 2 was employed. The test piece 7 is fixed to a grasping tool 8 and pressed by a rubber wheel 9 rotating at high speed. In this method, silica sand 13 is dropped from the hopper 10 onto the contact surface between the test piece 7 and the rubber wheel 9, and after a certain number of test rotations, the wear loss of the test piece is measured and evaluated. The reason why the wear powder was silica sand containing at least 90% of an SiO ₂ component is that SiO ₂ is Hv
It is a mineral product having a hardness of about 1000, which is different from a raw material for making iron, but can be tested and evaluated very quickly. Table 2 shows the wear test results, and Table 3 shows the rubber wheel wear test conditions. The component of the automatic welding molten wire applied to this example is 5.5C-24Cr-1.5W.
-2V-2Mo (% by weight), but about Hv8
It has a hardness of 60 and abrasion test results show that it has 3.3 times the abrasion resistance performance as compared to 30 chrome cast iron material.

[0015]

[Table 2]

[0016]

[Table 3]

Next, the embodiment shown in FIG. 3 will be described. The b portion of the hardfacing portion 6 on the sheet surface at the lower part of the small bell is a part where the wear loss is severe, and mechanically contacts the sheet surface at the lower part of the small bell cup, except when dropping and transferring the raw material for ironmaking. Seals the pressure inside the blast furnace. Therefore, both the sheet surfaces are required to have a surface roughness Ra number sequence of about 1.60 μm, and in the embodiment shown in FIG.
Although surface processing was performed by an automatic grinding process using a grindstone, there are very few such automatic grinding devices, and finishing by general mechanical cutting is desirable in order to suppress processing costs. Therefore, a build-up welding layer is provided on the uppermost layer portion of the portion b of the sheet surface 6 so that machining can be easily performed.
The hardfacing layer of v860 was stopped 3 mm lower than the other parts, and the uppermost layer was welded by submerged arc welding under the welding conditions shown in Table 4. As a result, the surface of the uppermost layer of the portion b had a hardness range of Hv420 to Hv520, and the surface could be finished by mechanical cutting at a lower cost than grinding by a grindstone.

[0018]

[Table 4]

FIG. 4 shows an embodiment in which the lower bell cup lower portion is manufactured according to the present invention. The small bell cup was a split type, and the lower part of the small bell cup was manufactured independently. The lower part 4 of the small bell cup, which was conventionally an integrally cast product of 30 chromium cast iron, was first cast with a cast steel SCW450, and was subjected to undercut for overlay welding. In the undercut portion 6, b
The lower portion was cut to 25 mm, and the other portion 6 was cut to a depth of 20 mm. The welding materials and welding conditions used for the overlay welding were almost the same as those of the embodiment shown in FIG.
Only the surface of portion b was finished by automatic grinding with a grindstone.

In the embodiment shown in FIGS. 1 and 4, a sealing material is applied to weld cracks on the surface so as to improve the adhesiveness of each sheet surface and to secure the airtightness of the blast furnace top pressure. To penetrate, an alumina ceramic adhesive was used as a sealing agent, and the opening of the weld crack was sealed and used.

In the embodiment, the small bell and the bell cup which are divided into two vertically are described. However, the present invention can be applied to the lower part of the one-piece small bell and the lower part of the small bell cup. is there. Further, in the embodiment, the welding method employs the submerged arc welding method. However, depending on the selected welding material, manual welding, CO ₂ welding or a non-gas arc welding method may be employed to secure a hardness of Hv 800 or more. good.

Further, in the case of a small bell and a small bell cup, which are integrally cast products of high chromium cast iron manufactured by a conventional method, when the seat surface reaches a wear limit due to use, the seat surface is not discarded, but is not discarded. In the repair, the present invention may be applied. That is, on the wear-degraded sheet surface, first undercut is performed, then hardfacing welding having a hardness of at least Hv800 is performed on the undercut surface of the high chromium cast iron, and a finishing process is performed by grinding with a grindstone. It may be reused by performing a sealing treatment.

[0023]

As described above in detail, according to the present invention, the wear resistance of the lower portion of the small bell and the lower portion of the small bell cup is remarkably improved, and the service life can be extended. And can be reused without having to be discarded at the time of arrival, resulting in a great economic effect.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a small bell illustrating an embodiment of the present invention.

FIG. 2 is a schematic diagram of a rubber wheel wear test.

FIG. 3 is a schematic cross-sectional view of a lower portion of a small bell illustrating an embodiment of the present invention.

FIG. 4 is a schematic sectional view of a lower portion of a small bell cup for explaining an embodiment of the present invention.

FIG. 5 is an assembly schematic diagram of a small bell and a small bell cup.

[Explanation of symbols]

1: Upper part of small bell 2: Lower part of small bell 3: Upper part of small bell cup 4: Lower part of small bell cup 5: Connection bolt and nut of split type small bell 6: Hardfacing weld layer (sheet surface) 7: Test piece 8: Grasp Tool 9: Rubber wheel 10: Hopper 11: Seal rubber 12: Raw material for steelmaking 13: Silica sand

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Shuji Yoshimori 1 Nishinosu, Oita, Oita City, Oita Prefecture Nippon Steel Corporation Oita Works (72) Inventor Yukio Emoto 2-27 Showa-dori 2-chome, Amagasaki City, Hyogo Prefecture No. Special electrode Co., Ltd. F-term (reference) 4K015 GA02

Claims (4)

[Claims] 1. A small blast furnace top charging device for holding an ironmaking raw material in a space formed by a small bell and a small bell cup, and lowering the small bell appropriately to transfer the ironmaking raw material downward. In bells and small bell cups, hardfacing welding is performed so that the deposited metal has a Vickers hardness of at least 800 or more on the surfaces of the sheet surfaces of the lower part of the small bell and the lower part of the small bell cup made of steel. A small bell and a small bell cup obtained by grinding a surface welded by overlaying. 2. A blast furnace furnace top charging device for holding an ironmaking raw material in a space formed by a small bell and a small bell cup, and lowering the small bell appropriately to transfer the ironmaking raw material downward. In the bell and the small bell cup, the hard metal overlay welding is performed so that the weld metal has a hardness of at least 800 or more in Vickers hardness on the surface to be each sheet surface of the steel small bell lower part and the small bell cup lower part. In the uppermost layer that has been hardened,
The weld metal layer has a Vickers hardness of 350 to 700, and the overlay is hardened and welded so that the overlay thickness is at least 3 mm or more, and then the hardened overlay welded surface is machined. Characterized small bell and small bell cup. 3. The small bell and the small bell cup according to claim 1, wherein a sealing treatment is applied to a surface subjected to grinding or mechanical cutting after hardfacing welding. 4. A small blast furnace top charging device for holding an ironmaking raw material in a space formed by a small bell and a small bell cup, and lowering the small bell appropriately to transfer the ironmaking raw material downward. In the method of repairing a bell and a small bell cup, when repairing a sheet surface which has reached a wear limit due to use, at least 800 or more Vickers hardness is deposited on a surface serving as a sheet surface of a lower portion of the small bell and a lower portion of the small bell cup. Of small bells and small bell cups of blast furnace top charging equipment, characterized in that hardfacing welding is performed so as to have a hardness, and then the hardfacing welded surface is ground or machine-cut and regenerated and repaired. Repair method.