JPH11290998A - Roll for twin roll type continuous casting - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a roll for twin roll type continuous casting, by which the damage of the roll edge part and a side weir refractory, the leakage of molten metal, etc., caused by thermal deformation of the roll edge can be avoided. SOLUTION: The roll end surface 9 being in contact with the side weir, has a tapered part inward of an obtuse angle α to the barrel surface of the roll as the cooling roll for twin roll type continuous casting. The angle α is decided as the following relations depending on the condition. That is, 0<α< tan<-1> (UL/h)+π/2, further α=θ+π/2, θMP<=θ<=θKP, further α=θMP+(θMP +θKP)/2+π/2. Wherein, (h) is the height in the end surface formed as the tapered part, UL is the min. gap which does not generate the molten steel leakage between the cooling roll and the side weir, θ is the leaning angle by projecting the roll end surface caused by thermal deformation of the cooling roll, θMP and θKP are the above angle θ at a meniscus part and a kissing part in the molten steel pool part, respectively.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for rapidly solidifying and cooling molten metal such as iron, non-ferrous metal or alloy after casting.
The present invention relates to a twin-drum continuous casting drum for forming a metal sheet having fine crystal grains and excellent workability and surface properties.

[0002]

2. Description of the Related Art A twin-drum continuous casting method for injecting molten metal between a pair of inwardly rotating cooling drums and rapidly solidifying the molten metal to produce a thin metal sheet is known as the Bessemer method. The method does not require a multi-stage hot rolling process as in the related art, and requires only a small amount of rolling to obtain a final shape, so that the process and equipment can be simplified.

FIG. 7 shows an example of an apparatus for performing the twin-drum continuous casting method. In this casting apparatus, a pair of cooling drums 1a and 1b rotating in opposite directions are arranged at appropriate intervals, and both ends in the axial direction of the drum are partitioned by side dams 2a and 2b to form a pool portion 3. Then, as shown in FIG. 8, when the molten metal 4 is rotated inward while pouring the molten metal 4 into the pool 3 from above, the injected molten metal comes into contact with the cooling drums 1a and 1b, and the heat is removed therefrom. As a result, solidified shells 5a and 5b are formed on the respective cooling drum surfaces. This solidified shell grows while cooling drum 1
The sheets are joined together with the rotation of a and 1b, and further reduced by the drum gap 6 to form a thin plate cast piece 7 having a predetermined thickness, which is sent out below the cooling drums 1a and 1b to produce a thin metal sheet.

[0004]

FIG. 5 (a)
As shown in FIG. 5, the cooling drum 1 receives a thermal load during casting and causes thermal expansion in the drum radial direction 8, and the end 9 of the cooling drum is moved in the drum axial direction as shown in FIG. 10 overhangs and causes deformation. At this time, the end surface 11a on the side weir side of the cooling drum is deformed like 11b, and comes into contact with the side weir surface at the edge 12. The surface of the side weir is made of refractory material 13 and oscillates in the inward direction 14 of the side weir to stabilize casting.

[0005] As shown in FIG.
2 damages the refractory surface 13 of the side weir by abrasion and breakage (indicated by reference numeral 16), and as shown in FIG. Oxidative hardening of the object surface, on the other hand, damages the drum edge, such as partly missing 18 and the like. When these damages occur, the frequency of the metal indenter 17 increases, causing a vicious cycle such as further advancing the damages, and finally casting becomes impossible.

As means for solving this problem, Japanese Patent Application Laid-Open No. 9-10
For example, forced lubrication between the cooling drum and the side weir disclosed in Japanese Patent Application Laid-Open No. 8788/1994, and thermal spray hardening of the end face of the cooling drum disclosed in Japanese Utility Model Application Laid-Open No. 6-5744 may be considered. In the structure that is inserted into the refractory surface 13 of the weir, a gap is generated due to a contact between the cooling drum and the side weir contact surface (15 in FIG. 5B), and the lubrication function is reduced, and the contact is caused by the contact. There is a possibility that the thermal spray hardfacing on the end face of the cooling drum is peeled off due to a local increase in surface pressure.

Therefore, the present invention flattens the contact between the drum edge and the side weir when hot, and advantageously prevents damage to the refractory of the drum edge and the side weir, and metal stake. It is an object of the present invention to provide a twin-drum continuous casting drum that can be avoided.

[0008]

The gist of the present invention for solving the above problems is as follows. (1) A twin-drum continuous casting drum, wherein a drum end surface that comes into contact with a side weir has a taper of an obtuse angle α with respect to a drum body surface. (2) The twin-drum continuous casting drum according to (1), wherein the taper angle α satisfies the range of the following expression. ^{0 <α <tan -1 (U} L / h) + π / 2 Here, h is the height of the end face tapering, the U _L is the minimum clearance that does not cause molten steel leakage between the cooling drum and the side dams. (3) The twin-drum continuous casting drum according to (2), wherein the taper angle α further satisfies the following expression. α = θ + π / 2 θ _MP ≦ θ ≦ θ _KP Here, θ is an angle at which the drum end surface that comes into contact with the side dam protrudes due to thermal deformation of the cooling drum, and
θ _MP and θ _KP are the meniscus of the molten steel pool portion and the angle θ at the kiss portion. (4) The twin-drum continuous casting drum according to (3), wherein the taper angle α further satisfies the following expression. α = θ _MP + (θ _MP + θ _KP ) / 2 + π / 2

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view showing a structure of an end portion of a cooling drum of the present invention. That is, the cooling drum 1 for twin-drum continuous casting is not receiving heat (cold).
, The end face 19a of the cooling drum where the drum end face contacts the side weir has a cooling drum structure having a taper of an obtuse angle α with respect to the drum body surface.

[0010] Here, the height of the end face tapering h, a minimum gap U _L which does not cause molten steel leakage between cooling drum-side weir. Since generally limit the gap U _L of the molten steel refers occurs is about 100 [mu] m, the condition that does not cause water pointing casting early by the taper caused, i.e. the upper limit of the alpha (alpha _UPPER) satisfies the following equation. _{h · tan (α UPPER -π /} 2) <U L Thus, the range of the taper angle becomes _{0 <α <α UPPER = tan} -1 (U L / h) + π / 2.

FIG. 2 shows a case where the end surface of the cooling drum in contact with the refractory surface of the side weir is perpendicular to the drum body surface in the cold state. 9 shows a change in overhang deformation of the end face in the state. When the edge of the rotating cooling drum is viewed in the direction of rotation, the overhang is minimum at the meniscus portion (MP) where the molten steel heat input occurs, and the overhang progresses rapidly with the rotation, and reaches a maximum at the drum kiss portion KP under the molten steel pool. Becomes

FIG. 3 corresponds to FIG. 2 and shows the change in the inclination θ of the end face where the cooling drum contacts the refractory surface of the side dam. When the edge of the rotating cooling drum is viewed in the direction of rotation, the inclination becomes the minimum value θ _MP at the meniscus portion (MP) where the molten steel heat input occurs, and the overhang rapidly progresses with the rotation,
The maximum value is θ _KP at the drum kiss portion KP below the molten steel pool.
The minimum value θ _MP of the inclination of the end face and the amplitude Δθ (= θ _KP −θ _MP ) of the meniscus to kiss portion are both zero at the beginning of the drum rotation (at the start of casting), and increase with the rotation (casting) and become stable. Become

As described above, the inclination θ during casting of the end face where the cooling drum contacts the refractory surface of the side dam is from θ _MP to θ
_Although it changes up to _{KP, since the} obtuse angle α with respect to the drum body surface must be uniquely determined, the α needs to be determined within a limit determined by the following equation. That is, α = θ + π / 2 θ _MP ≦ θ ≦ θ _{KP In} the range from the above θ _MP to θ _KP , the taper angle α is determined in order to cope with the average inclination during casting.
It is desirable to make the slope determined by the following equation. α = θ _MP + (θ _MP + θ _KP ) / 2 + π / 2

FIG. 4 shows the deformation of the end of the cooling drum for twin-drum continuous casting according to the present invention during heat and the state of contact with the side weir. End surface 19a of cooling drum in cold state
When it is hot, it protrudes in the axial direction 10, and the contact surface of the side weir surface with the refractory 13 becomes a flat 19b.

[0015]

Next, the results obtained when the end structure of the cooling drum having the structure shown in FIG. 1 is used for the twin drum type continuous casting cooling drum as described above will be described in detail. The structure shown in FIG. 1 was applied to a twin drum type continuous casting cooling drum having a drum width of 1300 mm and a diameter of 1200 mm. The height h of the end face tapering in the obtuse angle α with respect to the drum cylinder surface 10 mm, when the minimum gap U _L which does not cause molten steel leakage between cooling drum-side weirs and 100 [mu] m, cuttings cast initial water by taper due Is satisfied, that is, the upper limit of α (α _UPPER ) is α _UPPER = tan ⁻¹ (0.1 / 10) + π / 2 = 1.5808 rad = 90.57 degrees.

FIG. 3 shows the change in the inclination θ of the end face where the cooling drum contacts the refractory surface of the side dam in this embodiment. When the edge of the rotating cooling drum is viewed in the rotating direction, the inclination becomes a minimum value of 0.1 degree at the meniscus portion (MP) where the molten steel heat input occurs, and the overhang suddenly progresses with the rotation, and the drum kiss at the lower part of the molten steel pool. 0.25 max. In part KP
Degree. The minimum value θ _MP of the inclination of the end face and the amplitude of the meniscus to kiss portion of 0.15 degrees (= 0.25−0.1)
Initially, the rotation of the drum (at the start of casting) is zero, and increases and stabilizes with rotation (casting). Therefore, it may be determined in a range satisfying α = θ + 90 0.1 ≦ θ ≦ 0.25 ≦ 0.57.

Within the above range of 0.1 to 0.25,
In determining the taper angle α, it is desirable that the taper angle α be determined by the following equation in order to correspond to the average tilt during casting. α = 0.1 + (0.1 + 0.25) / 2 + 90 = 90.
3 In this case, the gap between the drums at the beginning of casting is 52 μm.
m, which is 100 μm or less, and there is no worry about the initial rinsing.

As a result of the casting by the present structure, the sharp edge does not damage the refractory surface of the side weir due to abrasion or breakage. Oxidation hardening did not cause damage such as partial chipping of the drum edge. However, the frequency of metal ingots was increased, and a vicious cycle such as further development of the damage was not caused. Thus, it was avoided that casting was finally disabled.

[0019]

As described in detail above, according to the present invention,
In consideration of the deformation of the drum edge during hot, in order to make the edge between the drum and the side weir flat by applying a reverse edge taper in the cold in order to make the contact between the drum and the side weir hot, the sharp edge is the fire resistance of the side weir The surface of the material is not damaged by abrasion or breakage, and damage such as partial chipping of the drum edge does not occur even when a foreign matter such as a metal ingot is caught during casting or the surface of the refractory is oxidized and hardened. For this reason, the frequency of the metal ingot is increased, so that a vicious cycle such as further advancement of the damage is not caused, and it is possible to prevent the casting from becoming impossible finally.

[Brief description of the drawings]

FIG. 1 is a diagram showing the structure of an end 9 of a cooling drum 1 according to the present invention in an overall view (a) and a partially enlarged view (b).

FIG. 2 is a diagram showing a change in overhang deformation of an end of a cooling drum.

FIG. 3 is a diagram illustrating a change in the inclination θ of an end surface at which an end of a cooling drum contacts a surface of a side weir;

FIG. 4 is a diagram schematically illustrating a deformed state of an end of a cooling drum according to the present invention.

FIG. 5 is a diagram schematically illustrating a state in which an end of the cooling drum is overhanging and deformed.

FIG. 6 is a diagram schematically illustrating a damaged state of a refractory on an end of a cooling drum and a surface of a side weir.

FIG. 7 is a diagram schematically illustrating a casting state by a twin-drum continuous casting apparatus in a perspective view.

FIG. 8 is a diagram schematically illustrating a state of casting by a twin-drum continuous casting apparatus in a cross-sectional view.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1, 1a, 1b Cooling drum 2a, 2b Side weir 3 Hot pool 4 Molten metal 5a, 5b Solidified shell 6 Drum gap 7 Thin plate slab 8 Radial expansion deformation 9 Drum end 10 Axial expansion deformation 11a, 11b Conventional Cold and hot positions of the drum end surface 12 Drum edge 13 Side weir refractory 14 Side weir surface vibration direction 15 Gap between drum edge and side weir surface 16 Wear and breakage of side weir surface 17 Metal stake during casting 18 Drum Edge chipping 19a, 19b Cold and hot position of drum end face according to the present invention

Claims (4)

[Claims] 1. A twin-drum continuous casting drum,
A twin-drum continuous casting drum, characterized in that the drum end surface in contact with the side weir has a taper at an obtuse angle α with respect to the drum body surface. 2. The twin-drum continuous casting drum according to claim 1, wherein the taper angle α satisfies the range of the following expression. ^{0 <α <tan -1 (U} L / h) + π / 2 where, h is the height of the end face tapering, the U _L is the minimum clearance that does not cause molten steel leakage between the cooling drum and the side dams. 3. The twin-drum continuous casting drum according to claim 2, wherein the taper angle α further satisfies the following expression. α = θ + π / 2 θ _MP ≦ θ ≦ θ _KP where θ is the angle at which the drum end surface that comes into contact with the side weir projects and tilts due to thermal deformation of the cooling drum.
θ _MP and θ _KP are the meniscus of the molten steel pool portion and the angle θ at the kiss portion. 4. The twin-drum continuous casting drum according to claim 3, wherein the taper angle α further satisfies the following expression. α = θ _MP + (θ _MP + θ _KP ) / 2 + π / 2