JPS6137355A - Cooling pad of belt type continuous casting machine - Google Patents

Abstract

PURPOSE:To obtain a slab stock having a flat surface shape by forming the discharge side of the water feed parts formed to a cooling pad into the shape expanding outward thereby decreasing the pressure loss in the water feed parts and executing cooling in a stable state. CONSTITUTION:Respectively plural pieces of water feed holes 12 and discharge holes 13 are formed approximately at equal intervals to the cooling pad 5 in the transverse direction of a belt 4. Cooling water is supplied from the same header 11 to an array of the holes 12 lines up in the transverse direction. The cooling water outlet side of the holes 12 is chamfered 12a and is so formed that the hole diameter increases successively toward the advancing direction of the belt 4. On the other hand, the discharge inlet side of the holes 13 is formed with an edge so that the diameter of the holes 13 decreases successively toward the advancing direction of the belt 4. The pressure loss in the water feed part is thus decreased and the driving power is correspondingly decreased. The cooling in the stable state against the fluctuation of load is made possible in the water discharge part.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a belt-type continuous casting machine, and particularly relates to a structure of a cooling pad for cooling a belt mold, which is suitable for casting slab materials with a flat surface shape. [Background of the Invention] Fig. 1 shows a schematic configuration of a belt type continuous casting machine. Molten steel 1 is introduced into a belt mold section constituted by a pair of endless belts 4 through a dandy pipe 2 and a nozzle 3. This belt casting hood is cooled by running water introduced into a gap 6 formed between a fixed plate provided at the back thereof, that is, a cooling pad 5 and the belt 4. The molten steel 1 is pulled out by pinch rolls 9 in a state in which a solidified shell 7 grows in the mold portion and an unsolidified portion 8 is completely solidified. The pair of belts 4 have guide rolls 10a and 10, respectively.
b. Guided by IOC and driven in synchronization with extraction.

The cooling water was supplied from the header 11 formed in the cooling pad 5 shown in FIG. 2 through the water supply hole 12, and the supplied cooling water formed a water film in the gap 6 and passed through. Afterwards, it enters the drain hole 13 and is discharged to the outside through a drain groove 14 formed at the back of the drain hole 13. The width of the spout can be changed by movably providing a short side 17 in cross-sectional views in the width direction of the mold shown in FIGS. 11 and 12, which will be described later.

The structure of the cooling pad 5 is conventionally disclosed in Japanese Patent Application Laid-open No. 57-10.
0851, as shown in FIGS. 3 and 4. In the figure, a plurality of oval grooves 15 with a short diameter a and a long diameter are arranged on the side of the belt 4 of the cooling pad 5 facing the belt 4 at approximately equal intervals in the vertical and horizontal directions.
The rows in the direction perpendicular to the direction of movement of the belt 4 alternately serve as water supply hole rows and drainage hole rows, and a water supply hole 12. is provided approximately at the center of each groove. A drainage hole 13 is formed. A gap 6 formed between the cooling pad 5 and the belt 4 having such a structure
A water film is formed on the belt mold, and the water film part has the cooling ability to suppress the temperature rise due to the heat received by the molten steel 1 of the belt mold, and supports the external load represented by the static pressure of the molten steel applied to the belt mold. It plays the role of forming a bearing that prevents wear due to sliding of the belt 4 by keeping the contact between the belt 4 and the cooling pad 5 in a non-contact state.

The dimensions and arrangement of the conventional rectangular groove 15 shown in FIG. 3 are as shown in FIG.
0~200+m, horizontal distance t1=200~4'00mm+
The vertical distance t2 was approximately 200 to 400 tm.

In the conventional cooling pad 5 having such a structure, emphasis was placed on the bearing function described above, and there remained a problem in the cooling function.

The strength of belt cooling is determined by the thermal conductivity αW due to the flow of cooling water.
The relationship between the thermal conductivity αW, the flow velocity vw, and the water film thickness δ is expressed by the following equation (1).

Expressing equation (1) in terms of flow rate Q per unit width gives the following equation (2).

That is, if the supplied flow rate Q is constant, the cooling intensity is proportional to the flow velocity vy, and is inversely proportional to the water film thickness δ. However, the water film thickness δ cannot be made too small considering the temperature rise of the coolant itself, and the lower limit is set at about 0.5 m+m.

In the cooling pad 5 having the conventional structure as described above, since the water supply hole 12 and the drainage hole 13 on the surface facing the belt 4 are provided with countersinks, the water is diffused radially near the water supply hole 12. Since stagnation occurs in the flow of the cooling water, a difference in cooling intensity occurs between the water flow portion formed in this spotted groove portion 15 and the water flow portion on the other surface. This difference in cooling strength causes the belt 4 to take on a wavy shape, and in the molten state at the initial stage of pouring molten steel, the liquid-tight contact between the metal belt 4 and the cooling pad 5 is inhibited, causing molten steel to leak and causing a casting accident. There is a risk of producing slabs with poor shape.

Furthermore, even when solidification progresses, a smooth slab surface cannot be obtained, resulting in quality deterioration.

In order to solve these drawbacks and improve the cooling capacity, it is necessary to significantly increase the flow rate), and the power required for this is even more powerful, which increases the manufacturing cost of the suspension material. was there.

Furthermore, the water film part has a uniform cooling water flow with sufficient cooling ability, and there are no irregularities caused by pressure distribution.
In order to have a uniform water film thickness of 1 m or less, it is possible to constantly manage the flow state of the water film and control the flow rate and pressure using external signals, but this method requires complicated equipment and is extremely expensive. It is not practical because it is a bulky item.

[Purpose of the invention]

The present invention has been made in view of the above circumstances, and its purpose is to provide a cooling pad for a belt-type continuous casting machine that has a simple structure and is capable of producing sprue material with a flat surface. be.

[Summary of the invention]

In the present invention, the shape of the discharge side of the cooling water supply part formed on the cooling pad of a belt-type continuous casting machine is expanded outward, and the discharge side of the cooling water supply part is further formed with a band-shaped recess. By connecting them, the intended purpose was achieved.

[Embodiments of the invention]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a cooling pad for a belt-type continuous casting machine according to the present invention will be described below with reference to the drawings.

An embodiment of the present invention is shown in FIGS. 5 to 17.

In this figure, parts that are the same as those of the conventional example shown in FIGS. 2 to 4 are designated by the same numbers. Since the construction of the casting machine is the same as that of the casting machine shown in FIG. 1 except for the cooling pad 5, the cooling pad 5, which is a feature of the present invention, will be described in detail.

゛ This cooling butt 5 is equipped with a belt 40 as shown in FIG.
A plurality of water supply holes 12 and a plurality of drainage holes 13 are formed at approximately equal intervals in the width direction, and cooling water is supplied from the same header 11 to a row of water supply holes 12 arranged in the width direction.

The cooling water outlet side of this water supply hole 12 has a diameter d relative to the water supply hole diameter dK.
A chamfer 12a of ic/2 to 2dx is provided, and the hole diameter dK is formed to gradually increase as the belt 4 advances in the traveling direction. On the other hand, drainage hole 13
An edge of C015 or smaller is formed on the inlet side of the drainage part, and the diameter dII of the drainage hole 13 is formed so as to gradually become smaller as the belt 4 advances in the traveling direction.

The drain holes 13 are connected to the same drain groove 14 in one row in the width direction of the belt 4 so as to drain the cooling water to the outside. As shown in FIG. 6, the water supply holes 12 and drain holes 13 are arranged at the same pitch and have the same diameter in a row in the width direction, and the drain hole positions in the width direction are the same as the water supply hole positions in the width direction. They are arranged in a houndstooth pattern approximately in the center between the water supply holes. In addition, the water supply hole 12
Among the water supply holes 12 located in the slab width constant area at the center, the belt sides of the water supply holes 12 adjacent to each other in the width direction are connected by a band-shaped recess 16, as shown in FIG.

When changing the slab width, the short sides 17 provided on both sides of the belt 4 in the width direction are moved to set the specified slab width as shown in FIGS. 11 and 12. The flow of cooling water at the end of the belt 4 on the outside of the short side 17, which is the non-contact area between the slab 7 and the belt 4 in FIG. It will be done. In this case, the relationship between the pressure ΔP and the flow rate Q is given by: If the pipe length of the water supply hole 12 is equal to the hole diameter dK, it is independent of the shape of the hole on the belt side, that is, the shape of the water supply jet side. In equation (8), ΔP is the pressure difference between the pressure P0 of the header part 11 and the water film part 6 shown in FIG.
At the belt end, ΔP −P.

becomes. CK is a coefficient determined by the shape of the inlet from the header portion 11 to the water supply hole 12, Q is the flow rate, N is the number of the water supply holes 12, dK is the hole diameter, and rw is the specific gravity of water.

The characteristics of the edge of the water supply hole on the belt side at the contact part with the slab are given by (4). In equation (4), Cw is a coefficient given by the shape of the water supply hole 12 from the header part 11 to the water film part 6, and B represents the width of the water film part. This coefficient Cw is determined by the shape of the water supply hole 12 as shown in FIG.
By changing from #) to b according to this embodiment, it decreases by about 20 to 50%.

Pressure loss represents the resistance to the flow of cooling water, and this pressure loss in the water supply section is calculated by ΔPI at the time it enters the water supply hole 12 from the header section 11 in FIG. There is ΔP2 that occurs at the time when the flow direction changes after the collision. ΔP shown in equation (8) is the sum of these ΔP1 and ΔP2.

In this embodiment, since the hole diameter d can be made small, ΔP1 can be made large and ΔP2 can be made small, thereby suppressing the unnecessary flow of cooling water to the outside of the short side 17 when the slab width is reduced for the same header pressure PG. becomes possible. Furthermore, the flow of cooling water in the water film portion 6 is as shown in Fig. 15, and the pressure distribution in the width direction is as shown in Fig. 16. In comparison, the case according to this embodiment is smaller, and uniform t camellia≠1 crucian μ. This is because cooling water flows more smoothly in the bm water supply hole shown in FIG. 13 than in the a type water supply hole as shown in FIG. 15.

If the slab width is not changed, or if the minimum width is the outlet side of the water supply hole 12 located on the inside of both short sides 17,
If they are connected by a band-shaped recess 16 as shown in FIG. 4, ΔPB shown in FIG. 16 will be further reduced and a more uniform flow of cooling water will be obtained.

The drainage section is the base pressure that determines the pressure of the entire water membrane group, and the overall pressure is determined by the pressure characteristics of the drainage section. 1st
Figure 7 shows the relationship between pressure P and water film thickness δ when the flow rate Q is constant. In the figure, the solid line a shows the characteristics of an A-type drainage hole, and the solid line A shows the characteristics of a B-type drainage hole when the hole diameters are the same. The broken line b' represents the characteristic when the hole diameter of the B-type drainage hole is made smaller than the hole diameter of the A-type drainage hole. As can be seen from FIG. 17, when the variation Δδ in the water film thickness is compared with ΔP given as the load variation, it is small in the a type, but large in the b type. In other words, when self-controlling load fluctuations by changes in the water film thickness, in the case of an am type, it is possible to cope with a slight fluctuation in δ, but in the case of a type b, it is not possible to cope with a large fluctuation, and the flat slab It is disadvantageous for manufacturing materials. Furthermore, if the load is significantly reduced, δ will significantly increase, resulting in a loss of cooling capacity.

Another embodiment of the invention is shown in FIGS. 18c-f.

C is an R-shaped seat 12a on the outlet side of the water supply hole 12, which can further reduce pressure loss and make the flow of cooling water smoother than a reed-shaped or tapered-shaped one.

d is an example in which the water supply hole 12 does not have a straight portion, and is adopted when the fixed plate 5 serving as a cooling pad is thin. e has the effect of smoothing the flow in the width direction and preventing stagnation between the water supply holes. f
is the same as C, but by increasing the exit diameter, Δ
Pi can be made much smaller.

〔Effect of the invention〕

As described above, according to the present invention, the shape of the discharge side of the cooling water supply section formed on the cooling pad of a belt type continuous casting machine is expanded outwardly, and the discharge side of the cooling water supply section is further expanded. Since the sides are connected by a belt-shaped concave part, it is possible to reduce the driving force by 10 to 30% by reducing the pressure loss in the water supply part, and in the drainage part, the water film thickness has rigidity against changes in load. The effect is great because it is now possible to cool the material in a stable state, and it is now possible to obtain a slab material with a flat surface.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram showing the configuration of a belt-type continuous casting machine, Fig. 2 is a partial vertical cross-sectional view showing the cooling pad part of Fig. 1, and Fig. 3 is a partial longitudinal cross-sectional view showing an example of the conventional cooling pad part. 4 is an explanatory view showing the arrangement of the water supply holes and drainage holes shown in FIG. 3, and FIG. Figures 6 and 7 are explanatory diagrams showing the arrangement of the water supply holes and drainage holes in Figure 5, and Figure 8 is an illustration showing the arrangement of the water supply holes and drainage holes in Figure 5.
IIM side view, FIG. 9 is a cross-sectional view taken along ■-■ in FIG. 7, FIG. 10 is a cross-sectional view taken along ■-■ in FIG. 7, FIGS. 11 and 12 are partial cross-sectional views in the width direction of FIG. 5, Fig. 13 is a diagram showing the shape of the water condensation hole, Fig. 14 is a diagram showing the band-shaped recess connecting the water supply holes, and Fig. 15 is a state diagram showing the flow of cooling water in the water supply part. In the case of the water supply hole (b) shows the case of the water supply hole according to this embodiment, and FIG. 16 is a pressure distribution diagram in the width direction of the water supply part (a). (b) is the same as the case of FIG. 15, FIG. 17 is a pressure characteristic diagram of a drainage hole, and FIG. 18 is a diagram showing the shape of a water supply hole according to another embodiment of the present invention.

Claims (1)

[Scope of Claims] 1. A belt mold part constituted by a pair of movable endless belts, and a plurality of water supply and drainage parts provided at the back of the belt to supply and drain cooling water for cooling the belt while supporting the belt. A cooling pad for a belt type continuous casting machine, characterized in that the shape of the discharge side of the water supply section formed on the cooling pad is expanded outward. cooling pad. 2. A belt mold part constituted by a pair of movable endless belts, and a cooling pad provided on the back of the belt and having a plurality of water supply and drainage parts for supplying and discharging cooling water for cooling the belt while supporting the belt. A cooling pad for a continuous belt casting machine, characterized in that the discharge side of the water supply section formed in the cooling pad is connected by a band-shaped recess.