JP5140025B2 - Method of spraying coating material on tundish - Google Patents

Description

  The present invention relates to a method for spraying a coating material on a tundish.

  The tundish used for continuous casting of steel has a structure in which a lining refractory is provided inside the iron skin. Furthermore, a coating layer is formed on the lining refractory for the purpose of preventing contamination of molten steel, facilitating the processing of remaining steel, protecting the lining refractory, and the like. The coating layer is formed of a coating material containing a refractory powder such as magnesia powder and a binder such as phosphate.

  As a construction method of the covering material, a spray construction method of spraying this through a nozzle is adopted. In spraying, for example, construction water is added to the coating material in the transport pipe reaching the nozzle and / or in the nozzle. The construction water has a role of attaching the covering material to the construction surface. The coating layer can be formed on the inner surface of the tundish by scanning the nozzle along the inner surface of the tundish.

  In FIG. 6, the nozzle scanning pattern disclosed in Non-Patent Document 1 is reproduced. Construction starts from the upper end of the side surface of the tundish 10, and construction progresses clockwise in the horizontal direction. A covering layer is formed on the side surface by repeating a cycle of descending by a predetermined dimension every time one round is completed. Then, the process proceeds to the construction on the bottom surface, and the coating layer is also formed on the bottom surface to finish the construction. Non-Patent Document 2 and Patent Document 1 also show similar procedures.

  Thus, conventionally, a coating layer is formed from the upper side to the lower side of the side surface of the tundish, and finally the coating layer is formed on the bottom surface. The reason for adopting such a procedure is as follows.

  The first reason is to form a smooth coating layer on the side surface. That is, the coating material may fall down downward due to gravity after being sprayed on the side surface. As shown in FIG. 6, if the construction is progressed from the upper side to the lower side, even if dripping occurs, the covering material is sprayed again on any part, so that the unevenness of the coating layer due to the dripping Can be prevented.

  The second reason is to prevent the scattered matter from remaining on the bottom surface. That is, when the covering material is sprayed on the side surface, it is inevitable that a part of the coating material rebounds from the side surface, and the rebounded scattered material falls downward. If the bottom surface is constructed after the side surface is constructed, even if scattered matter accumulates on the bottom surface during construction of the side surface, it can be filled with a coating layer when the bottom surface is constructed last. For this reason, it is possible to prevent the scattered matter from remaining on the bottom surface.

JP 59-70461 (see FIG. 5)

Kamada et al., “Development of automatic spraying system for tundish for continuous casting”, Refractory, 35-687, 1983, p19-24 (see FIG. 11). Ozaki et al., “About Tundish Automatic Spraying Machine”, Shinagawa Technical Report, No. 28, 1984, p95-104 (see FIG. 6)

  The coating layer is used after being heated and dried. The coating layer may be peeled off from the lining refractory during heat drying or when using a tundish over the lifetime due to melting damage.

  An object of the present invention is to provide a method for spraying a coating material onto a tundish that can prevent peeling of the coating layer.

FIG. 5A is a front view of a construction body made of a covering material. By moving the nozzle along a horizontal first dashed T _1, the side surface of the tundish, the construction member 20 that extends horizontally is formed. As described above, a part of the construction body 20 may become the dripping part 21a.

  FIG. 5B is a cross-sectional view taken along the line ZZ in FIG. The construction body 20 is thickest at the center and has a cross-sectional shape that becomes thinner as it approaches the upper and lower ends.

  Hereinafter, in the construction body, a portion having a thickness of 1% or more of the thickness at the center in the width direction is referred to as a central portion, and a portion having a thickness of less than 1% is referred to as a dust adhesion portion. In FIG. 5 (B), the code | symbol 21 shows a center part and the codes | symbols 22 and 23 show a dust adhesion part.

Returning to FIG. 5A, the description will be continued. Conventionally, mixture was allowed to cycle through the nozzle at a first height of the broken lines T _1, to scan the nozzle along the second dashed T ₂ of the lower than the first broken line T _1. Construction body formed along the second dashed line T ₂ are, partially overlap and construction body 20 which has already been formed.

Therefore, under the dust adhering portion 23 of the construction body 20 and anyone fall portion 21a, becomes be covered by the new construction element formed along the second dashed line T _2.

  As a result of intensive studies, the present inventors have found that the presence of the dust adhering portion 23 and the presence of the dripping portion 21a are one factor that causes peeling in the coating layer.

  That is, the dust adhering portions 22 and 23 contain almost no construction water, and fine particles are weakly adhered to the construction surface. Moreover, the dripping part 21a contains construction water excessively, and the adhesive force to a construction surface is weak. For this reason, the part which covered the dust adhesion part 23 and the dripping part 21a of the construction body formed last time among construction bodies has the weak adhesive force to a construction surface, and is easy to peel.

  In the formation of a general spray construction body, the presence of a dust adhering part or a dripping part can be ignored as a cause of peeling. However, the tundish coating layer, unlike ordinary sprayed constructions, is thin and has a thickness of, for example, about 10 to 30 mm. Therefore, it is difficult to ensure strength, and the presence of dust adhering parts and dripping parts is also peeled off. It can be a factor to bring about.

  Prior to the description of the present invention, terms used in this specification will be described by taking the situation shown in FIG. 1 as an example.

  FIG. 1 is a cross-sectional view of the nozzle and the side surface of the tundish. A coating material is sprayed on the side surface 12 of the tundish through the nozzle 2.

  The sprayed region refers to a region where the covering material is sprayed in the construction surface (here, the side surface 12). In detail, when the position of the nozzle is fixed and sprayed, and the construction body with the thickest part having a thickness of 200 mm is formed, an area having a construction thickness of 1 mm or more is defined as a sprayed area at the nozzle position. To do.

The angle α ° formed by the nozzle and the side surface is defined in the horizontal direction through the first virtual straight line S ₁ representing the central axis of the nozzle 2 and the intersection U between the _first virtual straight line S ₁ and the side surface 12 (FIG. 1). The angle between the virtual plane that includes both of the second virtual straight lines extending in the direction perpendicular to the paper surface and the side surface 12 on the bottom surface side of the tundish.

The divergence angle beta ° of coating material ejected from the nozzle, the third imaginary straight line perpendicular to point U as side surface 12, and the first virtual plane including both of the virtual straight line S ₁ in a plane (hereinafter, the incident 1), that is, in the cross-sectional view of FIG. 1, a virtual line segment S2 representing the distance from the upper end V of the sprayed region to the end surface 2a of the nozzle ₂ and the lower end W of the sprayed region. a virtual line segment S ₃ representing the distance to the end face 2a of the nozzle 2 from refers to the angle formed on the side surface 12 side.

When defining an angle α and β as described above, in a cross-sectional view taken along the incident surface, i.e., in the cross-sectional view of FIG. 1, the angle in which the virtual line S ₂ and the side surface 12 forms the bottom side of the tundish ( Hereinafter, it is referred to as an upper incident angle.) X is represented by α−β / 2.

  According to one aspect of the present invention, (a) a process of spraying a coating material onto the bottom surface of a tundish through a nozzle while scanning the sprayed area within the bottom surface and forming a coating layer on the bottom surface; ) After shifting the sprayed area to the side surface of the tundish, α−β / 2 ≧ 50 when the angle between the nozzle and the side surface is α ° and the spread angle of the coating material ejected from the nozzle is β ° A method for spraying a coating material on a tundish having a step of forming a coating layer on the side surface by repeating a cycle of rotating the sprayed region along the side surface and raising it every round under the conditions to satisfy Provided.

  Since the covering layer is formed from the lower side to the upper side, even if a drooping portion is generated in the construction body, the construction body formed in the next cycle does not cover the dripping portion. For this reason, it is possible to prevent peeling due to the sagging portion interposed between the coating layer and the side surface.

  By satisfying the angle α−β / 2 (example: upper incident angle X in FIG. 1) ≧ 50 °, the width of the dust adhering portion on the upper side of the construction body (example: dust adhering portion 22 in FIG. 5A) is reduced. Can be narrowed. For this reason, the peeling resulting from covering the dust adhesion part of the upper side of the construction body formed in the last cycle with the construction body formed in the next cycle can be suppressed.

It is a fragmentary sectional view which shows a nozzle and the side surface of a tundish. It is the schematic which shows the scanning pattern by an Example. It is sectional drawing which shows a part of spray construction apparatus by an Example. It is a graph which shows the relationship between the angle X of FIG. 1, and adhesive strength. (A) is a front view of the construction body formed in the side surface of a tundish, (B) is sectional drawing in the position of the ZZ line of (A). It is the schematic which shows the conventional scanning pattern.

FIG. 2 shows a nozzle scanning pattern according to the embodiment. FIG. 2 is a plan view of the tundish, and a solid line indicated by an arrow indicates a locus of an intersection between the central axis (first virtual straight line S ₁ ) of the nozzle 2 of FIG. 1 and the inner surface of the tundish.

  First, the nozzle is arranged at a position facing the starting point P in the bottom surface 11 of the tundish 10, and construction is started from the starting point P. While spraying the coating material from the nozzle onto the bottom surface 11, the sprayed region is scanned within the bottom surface 11. In the example of FIG. 2, the sprayed area is scanned according to a construction pattern that reciprocates in a zigzag manner in the longitudinal direction of the tundish 10.

  When the coating layer is formed on the bottom surface 11, the sprayed region is shifted to the side surface 12. Then, under the condition satisfying the upper side incident angle X ≧ 50 ° in FIG. 1, the cycle of rotating the sprayed region at a certain height position along the side surface 12 and increasing it by a certain dimension every time it makes a round is repeated. When the sprayed region reaches the end point Q at the upper end of the side surface 12, the formation of the coating layer is completed.

  In addition, although the example which finishes construction of the side surface 12 in 5 rounds for convenience is shown in FIG. 2, the dimension raised in every round and the round is not particularly limited.

  As described above, when the coating layer is formed from the bottom to the top, even if the construction body sags, the sagging will only flow on the surface of the construction body already formed. The construction body formed in the cycle does not cover the dripping part. For this reason, it is possible to prevent peeling due to the sagging portion interposed between the coating layer and the side surface.

  Moreover, the width | variety of the dust adhesion part 22 of the upper side of the construction body 20 of FIG. 5 (A) can be narrowed by setting it as the upper side incident angle X> = 50 degrees of FIG. For this reason, the peeling resulting from covering the dust adhesion part of the upper side of the construction body formed in the last cycle with the construction body formed in the next cycle can be suppressed.

  In FIG. 1, the upper incident angle X ≧ 50 ° or more can be realized by adjusting at least one of the angles α and β.

  Conventionally, since the angle α is 90 ° or less and the angle β / 2 is about 45 °, the upper incident angle X is at most 45 °. Under such conditions, by increasing the angle α to 95 °, the upper incident angle X can be set to 50 ° without changing the predetermined value 45 ° of the angle β / 2.

  Further, the upper incident angle X ≧ 50 ° or more can also be realized by reducing the angle β. Decreasing the angle β can be easily realized, for example, by using a previously-drawn nozzle, reducing the inner diameter of the nozzle, reducing the spraying pressure of the covering material, and the like.

  According to this method, there is a possibility that the coating layer formed on the side surface 12 has a sagging drop part, and there is a possibility that scattered substances rebound during construction of the side surface 12 accumulate on the coating layer on the bottom surface 11. Therefore, after forming the coating layer on the side surface 12, at least one of the process of smoothing the coating layer on the side surface 12 and the process of removing scattered matter from the surface of the coating layer formed on the bottom surface 11 may be performed. preferable.

FIG. 3 is a cross-sectional view showing a part of the spray construction apparatus according to the embodiment. A nozzle 2 is connected to a transport pipe 1 through which the covering material is transported by air. The first virtual straight line S ₁ representing the central axis of the nozzle 2 intersects with the third virtual straight line S ₄ representing the central axis of the transport pipe 1 at the corner portion 3.

  A construction water supply unit 4 is provided in the transport pipe 1. The construction water supply unit 4 includes a plurality of through-holes 4a formed in the transport pipe 1, a ring-shaped member 4b that covers an outer periphery of a portion of the transport pipe 1 where the through-holes 4a are formed, and a ring-shaped member 4b. And a construction water supply pipe 4c for supplying construction water. In the construction water supply unit 4, construction water is added to the covering material.

  An air supply unit 5 is provided in the nozzle 2. The air supply unit 5 includes a plurality of through-holes 5a formed in the nozzle 2, a ring-shaped member 5b that covers the outer periphery of the portion of the nozzle 2 where the through-holes 5a are formed, and compressed air into the ring-shaped member 5b. And a compressed air supply pipe 5c to be supplied.

  A vibrating member 6 is fixed to the inner surface of the nozzle 2. The vibration member 6 is made of a flexible material, specifically rubber, and is a notch that extends toward the other end in the one end side opening of a cone-shaped body whose opening at one end is narrower than the opening at the other end. A shape in which a plurality of layers are formed. The vibration member 6 is disposed between the one end and the other end at a position where the compressed air supplied from the through hole 5a is hit.

  The vibrating member 6 vibrates when the covering material collides with the vibrating member 6, and the vibration force promotes mixing of the covering material and the construction water supplied by the construction water supply unit 4. Moreover, the vibration energy of the vibration member 6 can be raised by supplying compressed air from the air supply part 5, and mixing with a coating | covering material and construction water can further be accelerated | stimulated.

  The mixing condition of the covering material and the construction water is also a factor that affects the width of the dust adhering portion 22 in FIG. 5A, similarly to the upper incident angle X in FIG. The better the coating material and construction water are mixed, the narrower the dust-adhered portion. For this reason, by using the nozzle 2 provided with the vibration member 6 as shown in FIG. 3, the effect of preventing the peeling of the coating layer can be further enhanced in combination with the upper incident angle X ≧ 50 shown in FIG.

  The following experiment was conducted to examine the relationship between the adhesive strength of the coating layer and the upper incident angle X in FIG.

  A nozzle 2 in FIG. 3 is used on a vertical test surface formed by stacking bricks vertically and horizontally, and the coating material is sprayed on the condition that the angle β / 2 in FIG. 1 is 45 °. After the nozzle 2 is scanned horizontally from one end to the other end of the test surface, a cycle of raising the predetermined dimension and horizontally scanning from the other end to the one end is repeated to form a coating layer on the test surface.

  After that, cut out a predetermined number of bricks where the construction body overlapped between cycles, heat and dry at 110 ° C, measure the shear strength of the interface between the brick and construction body, and measure between the cut bricks Find the average of the results.

  The average values of the shear strengths when the upper incident angle X is 35 °, 45 °, 50 °, 55 °, and 70 ° are respectively obtained, and the shear strength when the upper incident angle X is 50 ° is obtained. A value (adhesive strength index) obtained by dividing the average value by 100 is obtained. The upper incident angle X was changed by changing only the angle α.

  FIG. 4 shows a graph of the results. The horizontal axis represents the upper incident angle X, and the vertical axis represents the adhesive strength index. It can be seen that the adhesive strength is particularly increased when the upper incident angle X ≧ 50.

  As mentioned above, although the specific example of this invention was demonstrated, this invention is not limited to this. For example, FIG. 3 shows a dry-type spraying apparatus, but the present invention can also be applied to a wet spraying method in which dredged clay previously scoured with construction water is sprayed. It will be apparent to those skilled in the art that various combinations and improvements can be made.

DESCRIPTION OF SYMBOLS 1 ... Conveyance pipe, 2 ... Nozzle, 2a ... End face of nozzle, 3 ... Corner part, 4 ... Construction water supply part, 4a ... Through-hole, 4b ... Ring-shaped member, 4c ... Construction water supply pipe, 5 ... Air supply part DESCRIPTION OF SYMBOLS 5a ... Through-hole, 5b ... Ring-shaped member, 5c ... Compressed air supply pipe, 6 ... Vibration member, 10 ... Tundish, 11 ... Bottom surface, 12 ... Side surface, 20 ... Construction body, 21 ... Center part, 21a ... Who Falling part, 22 ... Upper dust adhesion part, 23 ... Lower dust adhesion part, T ₁ ... First dashed line, T ₂ ... Second dashed line, P ... Start point, Q ... End point, S ₁ ... First virtual Straight line, S ₂ , S ₃ ... virtual line segment, S ₄ ... third virtual straight line.

Claims (3)

(A) While spraying the coating material onto the bottom surface of the tundish through the nozzle, scanning the sprayed region within the bottom surface, and forming a coating layer on the bottom surface;
(B) After shifting the sprayed region to the side surface of the tundish, α−β / when the angle between the nozzle and the side surface is α ° and the spread angle of the coating material ejected from the nozzle is β ° The tundish is coated with a step of forming a coating layer on the side surface by repeating a cycle in which the sprayed region circulates along the side surface and is raised every time under a condition satisfying 2 ≧ 50. Material spraying method.   The spray construction method according to claim 1, wherein α ≧ 95 is also satisfied in the step (b).   Furthermore, after the step (b), at least one of (c) a process of smoothing the coating layer formed on the side surface and a process of removing scattered matter from the surface of the coating layer formed on the bottom surface. The spray construction method of Claim 1 or 2 which has the process to perform.

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