JP7440770B2 - Sub-material input chute - Google Patents

Description

The present invention relates to the structure of a chute for charging auxiliary raw materials into a converter furnace for steel manufacturing.

Since the auxiliary raw material input chute according to the present invention is disposed on the converter, the temperature is repeatedly raised and lowered from room temperature to nearly 1500° C., and cracks occur and are damaged due to thermal fatigue and the like. For this reason, they have conventionally had a cylindrical double structure, and cooling water has been poured into them, but this is not enough to prevent the occurrence of cracks. In addition, on the inner cylinder side of the chute, the auxiliary materials collide violently when inputting the auxiliary materials, causing significant abrasion and damage to the inner wall.Furthermore, the vibrations caused by the collision promote the growth of the aforementioned cracks, and cause cracks in the welded parts of the chute. may enter and cause damage.

For this reason, measures have been taken to improve cooling efficiency by devising a double-walled cooling water passage to avoid cracking, as in Patent Document 1, but this is not sufficient and the lifespan of the chute is extended. was desired. In addition, as a measure to protect the inner surface of the chute, a measure has been taken to place a ceramic block on the inner surface of the chute as in Patent Document 2, but although the ceramic block is less prone to cracking due to thermal fatigue, it is susceptible to cracking when auxiliary materials are added. Because they tend to fall off, they have a short lifespan and increase maintenance frequency and cost.

Utility Model Publication No. 54-6310 Utility Model Publication No. 60-25741

The present invention provides a long-life auxiliary material inputting chute that suppresses the propagation of cracks even if they occur and can continue to be used as a chute.

The inventors observed and studied the occurrence and progress of cracks in the chute, and as a result, they discovered a chute that can suppress the growth of cracks even if they occur. The details are as follows.

(1) An auxiliary raw material input chute for steelmaking, the inner wall of which is located within the range where the auxiliary raw material falls into contact with it from the top when the chute is installed on a converter, and directly below in the circumferential direction of the inner wall of the chute. °, there are multiple layers of metal welded or built-up welded so that the hardness increases toward the center of the chute, at least within ±40° on both sides of the lower half of the circumference of the inner wall of the chute. The lowest layer on the chute inner wall side of the plurality of layers is welded or built-up welded to strips of metal that are lined up in the circumferential direction of the chute inner wall so that the contact area is small. This is an auxiliary raw material inputting chute characterized by a structure.

(2) On the bottom layer of multiple layers on the inner wall side of the chute, metal strips with different cross-sectional shapes are arranged alternately, and the combinations of different cross-sectional shapes are square and circle, square and ellipse, and square and hexagon. It is preferable that it is either.

(3) The auxiliary raw material input chute has a double structure of an inner cylinder and an outer cylinder, and the inner wall of the inner cylinder has the plurality of layers, and a cooling water flow path is provided between the inner cylinder and the outer cylinder, or It is preferable that a cooling water flow path is arranged between the outer cylinder and the outer cylinder.

(4) Furthermore, it is preferable that the auxiliary raw material input chute has a one-layer structure of a cylinder in which a plurality of layers having different hardnesses are arranged on the inner wall, and a cooling device is arranged on the outer wall of the cylinder.

The present invention is preferable because even if a crack occurs, its propagation can be suppressed and the life of the chute can be extended so that it can be continued to be used as a chute.

FIG. 1 is a cross-sectional view of an auxiliary material inputting chute according to the present invention and a diagram showing an outline of its detailed structure. 1 is a diagram schematically showing an example in which the water cooling structure described in Patent Document 1 is applied as a water cooling structure for an auxiliary raw material inputting chute according to the present invention, and is a diagram showing a cross section thereof. FIG. 3 is a diagram schematically showing an example in which the water cooling structure described in Patent Document 1 is applied as the water cooling structure of the auxiliary material inputting chute according to the present invention, and is a diagram showing the A-A' cross section of FIG. 2.

The details of the invention will be explained below. Further, an example of the embodiment is shown in FIG. 1, and the following description will be made based on this.

The chute inner wall 3 has a plurality of layers having different hardness, and the hardness increases from the chute inner wall 3 toward the center of the chute. It is preferable that a plurality of metal layers are formed by welding or overlay welding so that the hardness increases from the inner wall 3 of the chute toward the center of the chute.

Although there may be a layer with the same hardness above or below the plurality of layers having different hardness, it is necessary that at least the uppermost layer 4 has a higher hardness than the lowermost layer 6. Further, it is preferable that at least the metal above the bottom layer 6 is formed into layers by overlay welding.

For example, in FIG. 1, the uppermost layer 4 is MT-700 (welding rod manufactured by Tokushu Electrode Co., Ltd.) with a hardness of HV550 to 800, and the middle layer 5 is MT-300 (same as above) with build-up welding of HV230 to 340. The round bar 8 and square bar 7 on the bottom layer are SS400. The chute 1 is SM490A, and for welding round bars and square bars as the bottom layer, a welding rod for all-position welding of mild steel and 49-MPa class high-strength steel (for example, SF manufactured by Nippon Steel Welding Industry Co., Ltd.) is used. -1 JIS Z3313) is preferably used.

Furthermore, the plurality of layers of different hardness disposed on the inner wall 3 of the chute have been found to be in the range where the auxiliary raw material comes into contact with falling from the top when the chute is installed on the converter, based on the observation of the fall of the auxiliary raw material on the inner wall 3 of the chute. In other words, it is preferable that they be arranged within a range of at least ±40° on both sides of the lower half of the circumference of the chute inner wall 3, assuming that the right bottom in the circumferential direction of the chute inner wall 3 is 0°. In addition, it is preferable to install the entire length in the longitudinal direction of the chute. However, depending on the shape of the chute 1 and the falling condition of the auxiliary materials, the length may be adjusted to some extent or the position may be shifted in the circumferential direction.

Among the plurality of layers of different hardness of the chute inner wall 3, at least the lowest layer 6 on the chute inner wall 3 side is divided into strips in the circumferential direction of the chute inner wall 3, and each adjacent strip has a small contact area. It has a structure in which metals are arranged circumferentially and welded or built-up welded. ``The contact area of each adjacent strip is small'' means that while maintaining appropriate bonding with the inner wall of the chute and the upper layer, the bonding area of adjacent strips of metal should be reduced while maintaining bonding. , is made as small as possible to ensure a materially discontinuous portion in the thickness direction of the layer and to prevent crack propagation from the upper layer. In order to make the contact area between adjacent sides small, metal strips with a hexagonal, circular, or elliptical cross section should be
・Hexagon, hexagon,...hexagon, hexagon/circle, circle,...circle, circle/ellipse, ellipse,...ellipse, ellipse/square, circle, square, circle,..., square, circle, square (example in Figure 1)
・Hexagon, square, hexagon, square, ..., hexagon, square, hexagon (・ellipse, circle, ellipse, circle, ..., ellipse, circle, ellipse ・Hexagon, circle, circle, hexagon, ...hexagon, circle, circle, hexagon An example of this would be to line them up and weld them to the inner wall of the chute.

The outline of the case where the above-mentioned "cross-sectional shape is square, circle, square, circle, ..., square, circle, square" corresponds to Fig. 1, and the square bars 7 and round bars 8 are arranged alternately in the circumferential direction. . Although they may all have the same cross-sectional shape, it is preferable to have no more than two consecutive same cross-sectional shapes in view of the effort involved in construction and the bonding strength with the chute inner wall 3 and the layer above. Moreover, the continuous use of square bars 7 is not preferable because the distance between adjacent square bars 7 becomes too wide due to the swelling during welding to the chute inner wall 3. Also, if adjacent square rods 7 or round rods 8 are first welded together and then attempted to be welded to the chute inner wall 3, the rectangular rods 7 or round rods 8 that are not welded to the chute inner wall 3 may Many metal parts are generated, which is also not desirable.

Regarding polygonal cross-sectional shapes, there is no problem if the cross-sectional shape is pentagonal or larger other than quadrangular, but considering the ease of welding etc. and the ease of processing into polygons, up to hexagonal shapes are acceptable. preferable.

It is preferable that the metal strips have different cross-sectional shapes arranged alternately, and in particular, if the cross-sectional shapes are a combination of square and circle, square and ellipse, or square and hexagon, the inner chute wall 3 This method is preferable because it allows stable bonding of strip-shaped metals and bonding of strip-shaped metals to each other.

The chute 1 for charging the auxiliary raw material is preferably provided with a structure for cooling the chute 1 itself. The auxiliary raw material input chute 1 has a double structure of an inner cylinder and an outer cylinder 9, and the inner wall of the inner cylinder has the plurality of layers, and a cooling water flow path is provided between the inner cylinder and the outer cylinder 9, or a cooling water flow path is formed between the inner cylinder and the outer cylinder. Preferably, a cooling water flow path is arranged between the cylinders. It is also preferable that the auxiliary raw material input chute 1 has a one-layer structure of a cylinder in which a plurality of layers having different hardnesses are arranged on the inner wall 3, and a cooling device is arranged on the outer wall 2 of the cylinder. For example, as shown in FIGS. 2 and 3, using the example of the water cooling structure described in Patent Document 1, a chute outer cylinder 9 is provided, a water conduit 11 is provided between the chute outer wall 2 and the chute outer cylinder 9, and the Cooling water (water supply) 10 is passed through the water conduit 11, and is discharged to the outside of the system through the cooling water (drainage) 12 between the chute outer wall 2 and the chute outer cylinder 9. FIG. 2 shows a cross section of the chute, and FIG. 3 shows a cross section taken along the line A-A' in FIG.

1 Chute 2 Chute outer wall 3 Chute inner wall 4 Top layer 5 Middle layer 6 Bottom layer 7 Square bar 8 Round bar 9 Chute outer cylinder
10 Cooling water (water supply)
11 Water pipe 12 Cooling water (drainage)

Claims (4)

An auxiliary raw material input chute for steelmaking,
The inner wall should be at least below the circumference of the inner wall of the chute, within the range where the auxiliary raw material falls into contact with it from the upper part when the chute is installed on the converter, and when the straight bottom in the circumferential direction of the inner wall of the chute is set to 0°. In the range up to ±40° on both sides of the half,
Multiple layers of metal are welded or built-up welded so that the hardness increases toward the center of the chute.
The lowest layer on the chute inner wall side of the plurality of layers has a structure in which welding or overlay welding is performed on strip-shaped metal strips arranged in the circumferential direction of the chute inner wall so that the contact area is small. Features an auxiliary material input chute. On the bottom layer of the multiple layers on the inner wall of the chute, metal strips with different cross-sectional shapes are arranged alternately, and the combinations of different cross-sectional shapes are square and circle, square and ellipse, and square and hexagon. The auxiliary raw material inputting chute according to claim 1, characterized in that: The auxiliary raw material input chute has a double structure of an inner cylinder and an outer cylinder, and the inner wall of the inner cylinder has the plurality of layers, and there is a cooling water flow path between the inner cylinder and the outer cylinder, or a cooling water flow path is formed between the inner cylinder and the outer cylinder. The auxiliary material inputting chute according to claim 1 or 2, characterized in that a cooling water flow path is arranged between the auxiliary raw material inputting chute. 3. The auxiliary raw material inputting chute has a one-layer structure of a cylinder in which a plurality of layers having different hardnesses are arranged on the inner wall, and a cooling device is arranged on the outer wall of the cylinder, according to claim 1 or 2. auxiliary raw material input chute.