JPS62176648A - Belt type thin casting billet continuous casting equipment - Google Patents

Abstract

PURPOSE:To prevent casting fins and thermal deformation of a belt by arranging a movable partition plate in a header of a cooling device and also a driving device, which shifts the partition plate in width direction of thin casting billet. CONSTITUTION:In order to make a cooling water rate per unit width flowed at both side parts of the moving belt larger than the rate flowed at a center part thereof, water supply tubes 16a, 16b, 17a, 17b at a side part capable of adjusting flow rate and water supply tubes 18, 19 at a center part having the same function are provided to the water supply headers 7, 8 and movable parti tion plates 9a, 9b, 10a, 10b are arranged. When a casting space 5 is determined by shifting side plates 3, 4 through side plate driving devices 15a, 15b, in accor dance with this determination, the partition plates 9a, 9b, 10a, 10b are shifted to suitable position by the partition plate driving devices 13a, 13b, 14a, 14b to balance the cooling water rate. In this way, the casting fins and the thermal deformation of the belt are prevented.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a belt-type thin slab continuous casting machine (so-called belt caster) that directly casts sheet bar-shaped slabs from molten metal. In particular, this is an improvement to the belt cooling device placed on the back of the belt to support the long side of the slab, and in particular, cooling that does not cause thermal deformation of the belt or hot water pouring even when casting with different widths. This is a proposal for continuous steel casting technology that makes it possible to

(Prior Art) A narrow belt caster using a pair of rotatable movable belts with part of the running path facing each other is shown in Fig. 2 disclosed in Japanese Patent Application Laid-Open No. 59-92154 There is something to show.

This known belt caster is equipped with a cooling device called a "cooling pad 7" which has a large number of supply/drain ports facing the belt on the back side of the movable (metal) belt. The belt is cooled by forming a running water film of cooling water between the cooling pad and the belt.

On the other hand, the present inventors made it possible to change the casting width by movably supporting the side plate for supporting the short side, thereby realizing casting of belt casters with different widths, which could be used for a wide range of applications. I did it like that.

However, with the different width casting, problems specific to it arose, as listed below.

(Problems to be solved by the invention) ■ Regarding prevention of overcasting, the external force applied to the movable belt on the pad side is caused by changes in the tension, thermal stress, static pressure of molten steel, etc. applied to the belt.
As shown in Figure (a), if we distinguish between (a) the area in contact with the slab or molten steel (area A), and (0) the areas at both side end portions of the movable belt adjacent to the area (area B), the two are different. Significantly different. Therefore, the thickness of the running water film in each area is not uniform, and especially when the thickness of the running water film at both end areas of the movable belt becomes thinner, the gap between the belt and the pad becomes large, and molten steel may enter there. This may cause casting cracks.

In addition, the movable belt 1 during casting in the areas A and B
The belt tension due to the thermal stress generated in the area is calculated as follows: If the belt temperature difference between areas A and B is ΔT (t),
Belt tension σ in each area. , σ, is given by the following formula.

Here, △σ is the stress term caused by thermal stress, and (3
) is shown by the formula.

△σ=αΔTE (3) Here, σ. : Initial tension of belt (kg-mar 2) B
: Belt width (mm) b: Slab width (mm) α: Linear expansion coefficient of the belt E: Young's modulus of the belt.

According to the research conducted by the present inventors, it was found that the running water film ejected from the cooling pad 7 had different effects between the running water film corresponding to area A and the running water film corresponding to the territorial area.

(a) The water film in region A has the effect of cooling and supporting the slab via the movable belt.

(b) The water film in region B has the effect of narrowing the gap between the side plate and the movable belt in the region where the side plate (short side of the mold) is present, thereby preventing hot water pouring.

Further, according to the research of the present inventors, when the cooling pad 7 is curved at the upper part and straight at the lower part as shown in FIG.
The cooling pad 7 is divided into three regions in the casting direction.

Zone 1: A region where the pad surface has a curvature R and the side plate exists at the belt side edge, Zone 2: A region where the pad surface is straight and the side plate exists at the belt side edge, Zone 3: The pad surface is straight, The necessary pressures PA and PR of the flowing water film to be supported in the zone A and zone 1 where no side plate is present at the belt side end are given by the following equations.

Therefore, PA and PB are not equal, and since σ, 〉〉σ0, it is usual that PA <p.

PA, P, and pressure P of the flowing water film in the width direction.

FIGS. 3(b) and 3(C) schematically show this.

In the case of Pw <pB, a hot water bottle is generated between the side plates 3, 4 and the movable belt 1.

In region A; Pw>>PA, the water film thickness becomes thick, fluctuations in slab thickness and thermal deformation of the belt due to insufficient cooling ability occur.

When Pw <<pA, water film breakage occurs and belt thermal deformation occurs.

As explained above, when the flowing water film sprayed from the cooling pad 7.8 is used to cool and support the slab, the pressure of the flowing water film is increased in the belt width direction with the boundary near the contact between the side plate and the molten steel. It became clear that there was a need to make a difference.

On the other hand, as a method of creating a difference in water film pressure in the width direction, the following methods (a) and (b) can be considered.

(a) A portion of the water supply header in the cooling pad 7.8 of each region A and B is isolated, and a larger amount of cooling water is supplied to the B region per unit width than to the A region.

(b) Part of the drainage header inside the pad 7.8 in each region A and B is separated by a partition plate, and the flow path resistance of drainage in region B is made larger than that in region A.

However, the pad (cooling device) structure shown in Fig. 3, etc., which has a fixed partition wall inside the header, can handle casting of a predetermined slab width, but when the slab width is changed, (a) If the slab width is made wider than the above prescribed slab width, 1 of area A
The pressure of the water film increases, and the thickness of the water film increases, resulting in poor slab shape and thermal deformation of the belt.

(b) If the slab width is made narrower than the above specified slab width, 1 of area B
The water film pressure at the end of the belt falls below a predetermined water film pressure, creating a gap between the side plate and the movable belt, and casting occurs.

A casting problem occurs.

Note that in zone 2, since the cooling pad 7 is straight, the PA and PB values are as follows.

PA Static pressure of molten steel g O However, since it is necessary to secure the force that presses the movable belt against the side end surface of the side plate, the following conditions must be satisfied: the water film pressure in area A and the water film pressure in area B. It is also necessary to ensure the same conditions as in Zone 1 above.

■ Regarding prevention of unbalance of cooling water flow rate, next, in zone 3 where the cooling pad is a straight section and there is no short side, the external force applied to the belt is PA molten steel static pressure PB0.

Fig. 4 shows a conventional cooling device, and when the casting width is wide W, the flowing water film in the liquid passage space between the movable belt and the cooling pad body covers the entire width direction (between a-a'). ), uniform cooling is achieved by receiving substantially the same internal pressure.

However, when the width W is narrow, the flowing water film flowing in the liquid passage space is a, a'.

The internal pressure is different between positions b and b' and between c and c', and a large amount of cooling water flows through the water inlets a, a', b, and b', which have small flow path resistance. There have been many cases in which the amount of cooling water is insufficient at the critical point c-c', which in turn leads to deformation and breakout of the movable belt, leading to problems in the casting operation.

Further, as a conventional cooling device, a partition wall 36a fixed to the water supply header in the cooling pad 7.8 as shown in FIG. 3(5) is used.

The structure with 3611 can only be used when the casting width is constant, and if the width of the slab is different, it has disadvantages such as thermal deformation of the movable belt, waste of cooling water flow, and defective slab shape. was.

■Prevention of belt thermal deformation Furthermore, in order to prevent belt thermal deformation across zones 1, 2.3, it is necessary to reduce Δσ shown in equation (3). To decrease Δσ, A.

It is necessary to reduce the temperature difference ΔT in region B. This △T
To reduce the water supply headers in areas A and B,
: +t L, it is effective to supply a fluid having a higher temperature than the temperature of the cooling fluid supplied to region A to region B.

However, a cooling pad whose inside of the header is partitioned with a fixed partition wall as shown in Fig. 3(b) cannot be used for casting with different widths.
Different width casting has problems such as thermal deformation of the belt, defects in the shape of the slab, and casting troubles due to casting.

In short, an object of the present invention is to overcome the problems currently faced by belt casters listed in items (1) to (4) above.

(Means for Solving the Problems) The present invention deals with the problems listed in (1) to (4) above as follows.

■Measures to prevent cast sticking (zone 1° corresponding to the short side of the mold) When changing the plate width, when moving the mold (short side) side plate, use the water supply header 78.8H internal partition 1-i9,1 of the cooling pad.

9b, lOa, and 10b are moved, and a cooling water flow ff1 (q-1;
0:, the flow rate (W water supply Rovich) is made larger than that in the area A where the slab and W movable belts 1 and 2 contact, and/or the drainage header internal partitions 1f9a to tob
The resistance of the drainage flow path located in the part corresponding to the mold side plate is made larger than the slab cooling part, that is, the widthwise center area of the movable belt 1.2, in order to accommodate the movement of the side plate due to the change in plate width. By moving in an area where the water film pressure is high, it was decided to achieve smooth continuous casting of thin slabs without any casting tension between the side plate and the belt.

■Measures to prevent unbalanced cooling water flow When changing the plate width, when moving the side plate, divider plate 9a inside the water supply header of cooling pad 7.8 below the mold side plate equivalent (zone 3)
.
Either supply the cooling water necessary for cooling to realize continuous casting of thin slabs without obstruction, and/or move the drainage header internal partition plates 9a to tab to reduce the drainage flow path resistance located between the regions. By making it larger than that of A, (
(a) The running water film in area A reduces the cooling water flow rate necessary for cooling the slab support belt or the slab; (b) The running water film in area B reduces the minimum cooling water flow rate necessary for lubrication of the movable belt or cooling pad. This makes it possible to obtain smooth continuous casting of thin slabs.

■Measures to prevent belt thermal deformation (Zones 1, 2.3) When changing the plate width, when moving the short side plate of the mold, the partition plates 9a to 10b in the water supply header are also moved accordingly, and the water supply in area B is By passing a cooling fluid at room temperature through the port 11 and a fluid at a higher temperature, such as hot water or steam, through the water supply port 11 in area A, the movable belt can be made smooth and thin without thermal deformation and without casting. We decided to realize continuous casting of slabs.

As a means for achieving the above-mentioned object that is well suited to the above-described measures, the present invention provides a rotary moving device with a cooling device having a large number of supply/drainage ports opening facing the belt on the back side. In a belt-type continuous thin slab casting machine of the type in which a casting space is constructed by arranging a pair of movable belts and a pair of side plates disposed along both side edges of the movable belts to face each other, the above cooling device is installed. A belt-type thin slab continuous casting machine is adopted, which is characterized in that a movable partition plate is housed in a header, and a drive device for moving the movable partition plate in the width direction of the slab is connected to the movable partition plate.

In the configuration according to the present invention, it is preferable that the movement of the movable partition plate is synchronized with the movement of both side plates during casting of different widths.

In addition, each section header partitioned by the movable partition plate is individually connected with a water supply pipe or a drain pipe in which a flow rate control valve or a throttle valve is inserted, and the movable belt of each section header is connected to a slab. Areas that are not in contact with the
It is desirable to configure the movable belt so that the pressure of the water film is high at the portion where the movable belt is just in contact with the side plate.

Furthermore, it is desirable that some of the section headers partitioned by the movable partition plate be connected to cooling water pipes, and the remaining sections should be connected to high-temperature fluid (hot water or steam) pipes.

(Function) Figures 1a to 1r show a part of the belt caster according to the present invention, which mainly includes a cooling device, but this is applicable to a narrow type belt caster as shown in Figure 2. This is an example.

The belt caster shown in Fig. 2 consists of a pair of movable metal bells (1.2) that are arranged opposite each other to form a gap for holding molten steel and its solidified slab over a predetermined distance. A pair of side plates 3.4 disposed between the belts near their side edges and movable in the width direction constitute a casting space 5 having a tapered tip, and the movable belt For cooling of 1.2, the cooling vat main body 7.8 is installed with a liquid passage space 6 on its back side! i
[It is made by placing i.

The casting space 5 is determined by the movement of the side plates 3.4 actuated via the side plate drives 15a, 15b, which at the same time constitutes the casting width. The present invention provides partition plates 9a, 9b, which are accommodated in the cooling pad bodies 7, 8 according to the casting width.
10a and 10b as well as partition plate drive devices 13a and 1
3b14a, 14b to a predetermined position.

(Example) Below, specific examples of prevention of overcasting, prevention of cooling water flow imbalance, and prevention of belt thermal deformation will be described.

■Specific example of prevention of casting As a water supply header for cooling pad 7.
Use one with the structure shown in the diagram. For example, when the partition plates 9a, 9b, 10a, and 10b are moved according to the casting width, the pressure of the flowing water film is adjusted to be greater in the portion corresponding to the casting space. That is, the movable belt 1.2
A larger amount of cooling water per unit width is allowed to flow to the sides (areas outside the casting space: areas that do not contact the slab) than to the center, and the pressure of the water film at the ends is reduced to the center. be larger than that of Note that a predetermined flow rate necessary for cooling the belt flows through the central portion. In order to achieve the above purpose, the water supply header 7.8 forming the cooling pad body is equipped with side water supply pipes 16a, 16b which can independently adjust the flow rate.
.

17a, 17b, central water supply pipes 18.19 are provided, and movable partitions 1f9a, 9b, loa, 10tl
need to be installed. The water supply pipes are individually connected to the side spaces 7h, 7h'8h, 8h' and the central header space (casting space) 78.8H on both sides. The side water supply pipes 16a...19 each have side flow rate adjustment valves 20a, 20b, 21a,
21b central flow rate control valves 22 and 23 are disposed to accommodate the size of each header space and the flow film pressure adjustment in each water area, which changes due to the movement of the partition plates 9a, 9b, lOa, and lob. Configure for individual control.

In addition, as another embodiment of this type, the shape of the partition plate and the header may be made as shown in FIG. 1b to define the effective width of the cooling water flow type increase. In this example, the water supply ports 11 in areas B other than the effective width β are closed, and a large amount of cooling water is allowed to flow from the water supply ports within the range of the effective width β.

Furthermore, in addition to the measures taken on the water supply means side, the drainage header 7
Regarding ', 8' as well, if the device having the structure shown in Fig. 1d is used in combination, the water film pressure on the side portion will further increase, making it more effective in preventing casting. In this example, the end headers 7h, 7h', 8h, 8h' and the center header space 711.8H include side throttle valves 28a, 28b, 29a, 29b that function independently, respectively. 30.31 shall be provided.

Further, FIG. 1e, which is another example using the drainage headers 7' and 8', shows partition plates 9a and 9 of the drainage headers 7' and 8'.
10b, 10a, and 10b are cylindrical in shape, which closes the drain port 12 over a certain distance, unlike in FIG. 1d. This cylindrical movable partition plate 9a',
9b', 10a', and lob' are moved to predetermined positions via partition plate drive devices 13a, 13b, 14a, and 14b as the side plates 3 and 4 move, similar to the function of the partition plate in FIG. 1a. The position where the drain port 12 is closed corresponds generally to the position of the side plates 3 and 4.

In this way, depending on the casting width, partitions 1f9a, 9b,
10a.

By moving the movable belt 10b, the drainage channels flowing to both side portions of the movable belt 1°2, that is, the drain ports 12, are closed, and the water film pressure thereon is increased compared to the central portion. The specific example of using the cylindrical partition plates 9a' to 1Ob' to block the side parts differs from the idea of isolating the header, and simply reduces the width of the central header space 7) 1.8) 1. The purpose is to change it according to the width.

■Specific example of preventing unbalanced cooling water flow rate Figure 1a is used as a water supply header. Partition plate 9a according to casting width
, 9b, 10a, 10b, the movable belt l does not require strong cooling.

The amount of cooling water flowing to the two side portions can be suppressed to the minimum necessary amount (formation of a running water film effective for achieving sliding lubrication between the belt and the pad). On the other hand, sufficient strong cooling can be achieved in the central part.

In addition, in order to achieve the above purpose, water supply header 7.8
Water supply pipes 16a, 16b, 17a, 17 connected to
b, 18°19 are movable partition plates 9a, 9b, lO
Both side header spaces 7 defined by a, 10b
h, 7h', 8h, 8h' and the central header spaces 7H and gH, respectively. Each water supply pipe 16a...19 has a prototype control valve 20a, 20b, 21a, 21b, 22.
23, the partition plates 9a, 9b, 1
It is configured to be able to be controlled separately to accommodate the size of the header space that changes due to the movement of 0a and 10b and the water film pressure adjustment in each watershed.

In addition, as a cooling pad, that is, a water supply header 7.8,
In this example, the structure shown in FIG. 1C may be used. Cylindrical partition plates 9a', 9b', lOa', lO
This is an example using b'. This cylindrical partition plate 9a/~l
Ob' is located closer to the side end in the width direction than the position corresponding to the side plate. This cylindrical partition plate only has the role of cutting off the water channels 7H and 81. Therefore, in this case, the side water supply pipes 16a to 17b and the side flow rate control valves 20a to 2
1b is unnecessary.

■Specific example of preventing belt thermal deformation Figure 1f shows a water supply header when hot water is heated at the end of the belt. End header 7h, 7h', 8h, 8h
' is supplied with hot water produced by a steam/water mixer via a cooling water pump 24. On the other hand, the center headers 711, 8H have partition plates (header partitions) 9a, 9b, 10a between the end on the hot water side to which cooling water is supplied via the cooling water pump 25 and the central part on the cold water side, and the fob is a side plate. 3
, 4, the partition plate drive devices 13a, 13b,
14a and 14b to a predetermined position, and the effective widths of 7H and 8H roughly correspond to the casting width.

(Effects of the Invention) As explained above and described above, according to the present invention, constant uniform cooling in the width direction can be achieved during casting of different widths, and as a result, prevention of overcasting, flow matrix imbalance, belt deformation, and This eliminates the possibility of causing other problems in the casting operation.

[Brief explanation of drawings]

Fig. 1 shows various specific examples of the cooling device used in the belt caster of the present invention, Fig. 1a to Fig. 1C are examples of water supply headers, Figs. This is an example using hot water. FIGS. 2(a) and 2(b) are perspective views of the belt caster, including an overall view (a) and a partially cutaway view. Figure 3 (a), (b), and (C) are all explanatory diagrams that clarify the influence of the belt width direction on the pressure of the running water film, and Figure 4 shows the influence of the running water film pressure when the side plate moves. FIG. 3 is an explanatory diagram for explaining the influence. 1.2... Movable belt 3.4... Side plate 5... Casting space 6... Liquid passage space 7.8... Cooling pad body (supply/drainage header) 7H, 811... Center Section header space 7h, 7h', 8b, 8h'
...Side header spaces 9a, 9b, 10a,
10b --- Partition plates 9a', 9b', to
a', 10b'...Cylindrical partition plate 11...Water supply port 12...Drain port 13a, 13b,
14a, 14b --- Partition plate drive device 15a,
15b...Side plate drive device 16a, 16b, 17a, 17b---Side water supply pipe 18.19...Central water supply pipe 1g', 19'...Central drain pipe 20a, 20
b, 21a, 21b... Side flow rate control valves for water supply 22, 23... Central flow rate control valves for water supply 24, 25
...Cooling water pump 26...Steam blowing nozzle 27...Cooling water pits 28a, 28b, 29a, 29b...Drain pipe side throttle valve 30.31...Central drain pipe throttle valve 4th figure

Claims (1)

[Scope of Claims] 1. A pair of movable belts that rotate in a circular motion, each of which has a cooling device on the back surface of which has a large number of supply/drainage ports opening facing the belts, and a cooling device that has a number of supply/drainage ports facing the belts. In a belt-type continuous thin slab casting machine of the type in which a casting space is constructed by arranging a pair of side plates facing each other, a movable partition plate is housed in the header of the cooling device, and a movable partition plate is is a belt-type thin slab continuous casting machine characterized by being connected to a drive device that moves the belt in the width direction of the slab. 2. The continuous casting machine according to claim 1, wherein the movement of the movable partition plate is synchronized with the movement of both side plates during casting of different widths. 3. Each compartment header partitioned by the movable partition plate is individually connected to a water supply pipe or a drain pipe in which a flow rate regulating valve or a throttle valve is inserted, respectively. The continuous casting machine according to any of paragraph 2. 4. The continuous casting machine according to claim 3, wherein a portion of the section header in which the movable belt is not in contact with the slab is configured as a low-pressure cooling water supply area. . 5. The continuous casting machine as set forth in claim 3, wherein the continuous casting machine is configured such that the water film pressure is high at a portion of the section header where the movable belt is just in contact with the side plate. 6. Either one of claims 1 or 2, characterized in that, for each compartment header partitioned by the movable partition plate, some are connected to cooling water pipes, and the rest are connected to high-temperature fluid pipes. Continuous casting machine described in Crab. 7. The continuous casting machine according to claim 6, wherein the high-temperature fluid is hot water. 8. The continuous casting machine according to claim 6, wherein the high-temperature fluid is steam.