JP3540980B2 - Twin-drum continuous casting method and apparatus - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention expands the limit of the amount of casting limited by the damage and wear of the side dam refractory that slides in contact with the drum end surface in casting a thin strip slab by a twin-drum continuous casting apparatus, and performs long-time casting. Method and apparatus for enabling.
[0002]
In casting of a thin strip by a twin-drum continuous casting apparatus, a pair of side dams are pressed against both end surfaces of a pair of drums to form a pool, and a pair of drums is formed while continuously supplying molten steel to the pool. After rotation, a pair of solidified shells formed along the peripheral surface of the drum are pressed at the minimum gap portion (drum kiss point) of the drum to form a slab.
[0003]
[Problems to be solved by the invention]
In twin-drum continuous casting, it is important to improve the production efficiency by reducing the cost of consumables and performing long-time casting. Refractory life was a major factor influencing casting time and consumable costs.
[0004]
The types of wear that determine the service life of the side dam refractories are listed below.
(1) The lowermost end of the side refractory is broken by the downward force received from the drum and the solidified shell.
(2) The metal that has been generated and adhered to the side refractory near the drum peripheral surface peels off and falls off, and when the metal passes through the gap between the drums, the side refractory is directly pulled and destroyed.
(3) When the above-mentioned metal passes through the gap between the drums, the gap between the drums is temporarily widened, and the end face of the drum rides on the unworn portion of the refractory on the side dam, and molten steel enters the gap generated there and the ground. It becomes gold and damages refractories on side dams.
(4) When the expanded drum returns, it overhangs and collides with the side dam refractory, destroying the refractory.
(5) When the solidified shell formed at the end of the peripheral surface of the drum and the semi-solidified molten steel attached to the vicinity of the surface of the shell move together with the drum, the side dam refractory is damaged by erosion or erosion.
[0005]
As the damage of the refractory of the side dam progresses, molten steel invades there and becomes slab, and the slab damages the refractory of the side dam, resulting in poor sealing and leakage of the molten steel. Once the molten steel leaks out, the seal deteriorates abruptly, making it impossible to continue casting. Further, as shown in FIG. 12, when the damage of the side dam refractory 4 progresses, the damage extends to a portion in contact with the drum end surface 1a, molten steel enters the damaged portion d, and the solidified shell g is moved to the drum end surface. The phenomenon that goes around to the side occurs. When the solidified shell g wrapped around the drum end face side is discharged together with the slab from the drum kiss point, the solidified shell g is caught on the drum end face, and as a result, a phenomenon in which the slab wraps around the drum occurs, which hinders continuation of casting, A phenomenon occurs in which the slab edge is torn.
[0006]
Conventionally, refractory materials have been improved in order to extend the life of refractories for side dams, but such damage has not been completely prevented. On the other hand, as a method of extending the life of refractories of the side weir by improving the usage method of the side weir, the lower end of the side weir is provided to extend below the drum kiss point, and the side weir is provided according to its wear rate. A method of shifting a damaged portion of a side refractory upward by slowly raising the refractory so as to always expose a new refractory surface is known, for example, from Japanese Utility Model Laid-Open No. 4-43447.
[0007]
However, when the lower end of the side weir is provided so as to extend below the drum kiss point, an arc-shaped wear mark corresponding to the drum end face is also formed on the extended portion, and the drum end face fits into the wear mark. If the side weir is raised in this state, abrasion marks will push up the drum peripheral portion below the drum kiss point, so that the side weir cannot be raised unless the refractory is easily worn. In addition, since the side weir refractory is usually abrasion-resistant, it is extremely difficult to ascend.
[0008]
In order to facilitate the upward shift of the side weir, it is necessary to position the lower end of the side weir at the drum kiss point or above the drum kiss point. As a result, the lower end of the side weir reaches the uncompressed position of the shell, causing molten steel leakage, and the stroke of the side weir that can be raised is small.
The present invention extends the life of the side weir by preventing damage to the refractory of the side weir, eliminating problems such as molten steel leakage due to the upward shift of the side weir, and expanding the liftable stroke of the side weir. The task is to achieve this.
[0009]
[Means for Solving the Problems]
The present invention that solves the above-mentioned problems is a twin-drum continuous casting apparatus in which a pair of side weirs is pressed against both end surfaces of a pair of drums, and each lower end surface of the pair of side weirs is formed as an inclined surface in a chamfering direction. It is characterized by having done. According to the present invention, casting is started in a state where the upper edge of the inclined surface is positioned at the drum kiss point, and the side weir is shifted upward at a speed corresponding to the wear speed, whereby the upper surface of the inclined surface is shifted. Since the edge shifts downward with wear, even when the side weir is shifted upward, the lower end of the side weir can be maintained at the drum kiss point. In addition, since the lower end surface of the side weir is formed as an inclined surface, it is possible to prevent the side weir refractory from being lost due to the downward force of the drum and the solidified shell.
[0010]
Further, the present invention provides a twin-drum continuous casting apparatus in which a pair of side dams are pressed against both end surfaces of a pair of drums, wherein a seal portion projecting in a ring shape is provided on an outer peripheral portion of each end surface of the pair of drums, a protrusion provided along the contact surface between each of the seal portions of the pair of side weirs, characterized in that the formation of the outer surface of the projecting portion by the inclined surface of the chamfered direction. According to the present invention, when the side weir is shifted upward at a speed corresponding to the wear, the side edge of the inclined surface can be maintained at the peripheral edge of the seal portion. The surface width can be maintained. Further, since there is provided a protrusion on the contact surface between the drum seal portion of the side weirs refractory, the protrusions wear grooves (not wear portion) is not formed. For this reason, it is possible to prevent the seal failure due to the drum gap being opened by the above-described metal biting and the drum end surface riding on the unworn portion of the side dam refractory.
[0011]
The present invention also provides a twin-drum continuous casting apparatus in which a pair of side dams are pressed against both end surfaces of a pair of drums. A stepped portion for crimping the shell is provided, and each of the pair of side weirs is provided with a lifting drive means for raising the side weir along the drum end surface.
[0012]
Further, the present invention provides a method of casting a strip slab by a twin-drum continuous casting apparatus in which a pair of side weirs are pressed against both end surfaces of a pair of drums. Casting is started in a state in which a stepped portion for pressing a pair of solidified shells at both ends of the peripheral surface is provided, and a lower end of each of the pair of side weirs is positioned within a range of 20 mm above a drum kiss point. Each of the pair of side weirs is raised according to its wear rate.
[0013]
When stepped portions are provided at both ends of the peripheral surfaces of the pair of drums as in the present invention, the step at which the shell press-bonding points at both ends of the drum can be shifted upward. The side weir can be shifted upward by an amount corresponding to the shift.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 is a side view of a side weir portion of a twin-drum continuous casting apparatus according to the present invention, and FIG. 2 is a front view taken along the line II of FIG. The inside of the pair of drums 1 and 1 shown in FIGS. 1 and 2 is cooled by a cooling medium such as water, and rotates in opposite directions. At both ends of the peripheral surfaces of the pair of drums 1 and 1, there are provided stepped portions 1b that can shift the shell crimping start point upward by pressing the solidified shells at both ends of the peripheral surfaces. . Desirable dimensions of the stepped portion 1b vary depending on the thickness of the cast plate. When the thickness of the cast plate is 1.0 to 6.0 mm, the width is about 3 to 15 mm and the height is about 0.1 to 0.5 mm. In order to secure a sealing surface pressure (pressing surface pressure) with the side weir 2, a ring-shaped projecting seal portion 1 c having a width of about 5 to 20 mm is provided on the outer peripheral portion of both ends of the drum (see FIGS. 4 and 5). ) Is provided.
[0015]
A pair of side weirs 2 (only one is shown) shown in FIG. 2 has a refractory case 3 filled with an irregular refractory 5, a refractory brick 6 fixed to the irregular refractory 5, and a refractory brick 6. A groove (not shown) is provided in a portion facing the seal portion 1c, a plurality of ceramic plates 7 such as BN are fixed in the groove, and a substantially V-shaped projection 8 is formed by the plurality of ceramic plates 7. It is configured. The projections 8 of the ceramic plate 7, to ensure the strength of the ceramic plates 7, and, for facilitating the alignment of the surface and the seal portion 1c surfaces of the projections 8, the ceramic plate 7 Only protrudes in the center of the width.
[0016]
A stiffener 9 for preventing thermal deformation of the side dam 2 is fixed to the rear side of the refractory case 3 shown in FIG. A central portion of the stiffener 9 is supported by a support shaft 11 fixedly supported by an elevating support frame 10. Two upper and one lower points of the stiffener 9 are fixed and supported by the elevating support frame 10. It is supported by a hydraulically or electrically driven pressing device 12.
[0017]
The lifting / lowering support frame 10 is connected to a hydraulically or electrically driven lifting / lowering drive unit 14 having a lower portion guided by the vertical guide 13 and fixed to the bottom surface of the vertical guide 13. As described above, the side weir 2 is configured to be pressed against the end surfaces of the pair of drums 1 by the pressing device 12 and to be able to move up and down along the drum end surfaces by the lifting drive unit 14.
[0018]
FIG. 3 is an enlarged view of a lower cross section of the side weir 2 shown in FIG. As shown in the figure, the lower end surface of the substantially V-shaped projection 8 in the side weir 2 is formed by an inclined surface 8a in the chamfering direction. Before starting the casting, the upper end 8b of the inclined surface 8a is positioned at the drum kiss point kp to start casting, and the side weir is raised at a speed corresponding to the abrasion speed of the projection 8a. At the drum kiss point kp. Further, since the lower end surface of the projection 8 is formed as an inclined surface, it is possible to prevent the side dam refractory from being lost due to the downward force of the drum and the solidified shell.
[0019]
FIG. 4 and FIG. 5 show plan sections taken along the arrows II-II and III-III of FIG. 2, respectively. As shown in the figure, the outer surface of the substantially V-shaped projection 8 in the side weir 2 is formed by an inclined surface 8d. When the upper end 8b of the inclined surface 8a shown in FIGS. 2 and 3 is matched with the drum kiss point kp before the start of casting, the side edge 8e of the inclined surface 8d and the peripheral edge 1d of the seal portion are matched, and the sliding of the projection 8 is performed. It is formed so that the dynamic surface width and the sliding surface width of the seal portion 1c match. Therefore, when the side weir 2 is raised at a speed corresponding to the abrasion speed of the projection 8, the positional relationship between the side edge 8e of the inclined surface 8d and the peripheral edge 1d of the seal portion is maintained throughout casting, and as a result, In addition, it is possible to prevent the seal failure by maintaining the initial seal surface width. Further, since the sliding surface width of the protrusion 8 and the seal portion 1c match, no wear groove (unworn portion) is formed in the protrusion 8. For this reason, there is no problem that the drum gap is opened due to the ingot of metal and the seal portion 1c rides on the unworn portion of the protruding portion 8 to cause poor sealing.
[0020]
Next, a method of casting a thin strip by the twin-drum continuous casting apparatus of the present invention will be described. As shown in FIGS. 1 and 2, the upper end 8 b of the inclined surface 8 a is positioned within a range of 20 mm above the drum kiss point kp, and the side weir 2 is pressed by the pressing device 12 to about 0.1 to 0.2 kg / mm ² . As shown in FIG. 7, the molten steel R is continuously supplied into the pool P while being pressed against the drum end surface 1a by pressure, and a solidified shell g is generated on the peripheral surfaces of the pair of drums 1 and 1, and Is rotated in the direction of the arrow to press the pair of solidified shells g and g together at the drum kiss point kp to cast a thin strip s.
[0021]
The projections 8 of the side weirs shown in FIGS. 4 and 5 due to the abrasion due to sliding contact with the seal portion 1c of the drum and erosion and erosion caused by a solidified shell or the like formed at the end of the drum due to casting. As shown in FIG. 12, the refractory damaged portion d is formed and proceeds, and if left as it is, troubles such as molten steel leakage occur.
[0022]
Therefore, by operating the elevation drive means 14 shown in FIG. 1, the side weir 2 is continuously driven at a speed corresponding to the damage speed of the projection 8 (elapsed casting time), for example, at a slow speed of 1 mm or less per minute. Or raise it intermittently. As shown in FIG. 6, when the side weir 2 is shifted from the position A (broken line) to the position B (solid line), the damaged portions ab generated at the position A move to a′-b ′. As a result, the surface of the side weir refractory that is in sliding contact with the seal portion 1c of the drum becomes a new lower surface that has not been in contact with the seal until now.
[0023]
As the side weir 2 rises, the lower end of the side weir 2 rises. In the conventional drum, when the lower end of the side weir 2 rises beyond the drum kiss point kp shown in FIG. 6, molten steel leaks from the lower end of the side weir 2 easily. However, in the present invention, as shown in FIGS. As described above, since the lower end surface of the projection 8 is formed by the inclined surface 8a, even if the lower end of the side weir 2 rises, molten steel does not leak.
[0024]
FIG. 3 is an enlarged view of the inclined surface 8a during casting. In the figure, the portion surrounded by a broken line is a portion where the refractory is worn. In FIG. 3, at the beginning of casting, the upper end 8b of the inclined surface 8a is located at the drum kiss point kp. However, when the side weir 2 is raised at a speed corresponding to the wear speed of the projection 8, the drum end surface 1a (1c) is obtained. The upper end 8b of the inclined surface 8a that comes into sliding contact with the main body moves along the inclined surface 8a to maintain the position of the drum kiss point kp. Finally, when the lower end 8c of the inclined surface 8a reaches the drum kiss point kp, the life of the side weir 2 ends.
[0025]
In the conventional side weir, as shown in FIG. 8, the width of the sliding surface (seal surface) of the projection 8 changes from w _{1 in} FIG. 8A to w _{2 in} FIG. And the sealing function is reduced. When the side weir 2 is further raised, the projections 8 are pushed into the drum gap k and completely lose the sealing function.
[0026]
According to the second aspect of the present invention, as shown in FIGS. 2, 4 and 5, the outer surface of the projection 8 is an inclined surface 8d. FIG. 9 shows an enlarged view of the inclined surface 8d. In FIG. 9, a portion surrounded by a broken line is a portion where the refractory is worn, and the seal surface width of the protrusion 8 before the wear is w ₁ , but the side dam is at a speed corresponding to the wear speed of the protrusion 8. 2 result of the increased shift, seal surface width after wear is also w _1. Thus, the outer surface of the projecting portion 8 by an inclined surface 8d, it is possible to eliminate the decrease in the sealing surface width w ₁ with increasing shift of the side weirs 2.
[0027]
In the third and fourth aspects of the present invention, as shown in FIGS. 1 and 5, stepped portions 1 b are provided at both ends of the peripheral surface of the drum 1. The stepped portion 1b, the solidified shell g of the drum end portions, which when pressed the g together, as shown in FIG. 7, the shell crimping starting point is shifted upward from p ₁ to p _2. As a result, even if the side weir 2 is shifted from the position A to the position B as shown in FIG. 6, no molten steel leaks from the lower end of the side weir 2, and as shown in FIG. Can be increased from h ₁ to h ₂ .
[0028]
In the present invention, when the side weir 2 is shifted upward, it is desirable to start casting with the upper end 8b of the inclined surface 8a located within a range of 20 mm above the drum kiss point kp. The reason is that, in the initial state of casting, when the solidified shell g is pressed at the drum kiss point kp, “widening” occurs near the drum kiss point kp due to semi-solid rolling, and at this time, the upper end 8b of the inclined surface 8a rises. If it is located below the drum kiss point kp, this "widening" force acts on the refractory (side weir) and damages the refractory or pushes out the side weir, deteriorating the sealing performance. Because you do.
[0029]
Further, when the upper end 8b of the inclined surface 8a is positioned below the drum kiss point kp at the start of casting, an arc-shaped wear mark formed corresponding to the drum circumferential edge below the drum kiss point kp of the projection 8 is formed. This is because it becomes an obstacle to the rise of the side weir. The reason why the upper end 8b of the inclined surface 8a is set within 20 mm above the drum kiss point kp is that if the upper end 8b is located beyond 20 mm, unsolidified molten steel leaks out from the inclined surface 8a and the sealing performance is reduced.
In the above description, the inclined surface 8a on the lower end surface and the inclined surface 8d on the outer surface of the protruding portion 8 are inclined surfaces, but may be stepped with a plurality of steps instead of the inclined surfaces. In this case, if the step exceeds 5 mm, chipping is likely to occur, so the step is desirably 5 mm or less.
[0030]
【Example】
FIG. 10 shows an example of an invention in which a slope is provided on a lower end surface and an outer surface of a side weir projection, and a stepped portion is provided on both ends of a drum peripheral surface in a method of ascending and shifting a side weir. 7 shows a shift amount of side weir rise (amount of rise of side weir when molten steel leakage starts) in a comparative example in which no portion is provided. According to the invention example, the shift amount of the side weir rising shift can be increased about three times as compared with the conventional case. FIG. 11 shows the relationship between the upward shift amount of the side weir and the casting time extension rate when the casting time of the comparative example is set to 1. According to the invention, the casting time can be extended 1.5 to 6 times as compared with the comparative example.
[0031]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, in a twin drum type continuous casting, the life of a side dam refractory can be extended, as a result, equipment cost can be reduced sharply, and production efficiency can be improved by continuous casting for a long time. Can be greatly improved. Furthermore, it is possible to stably perform casting by avoiding troubles such as winding of the slab around the drum due to erosion and erosion of the refractory of the side dam and stopping of casting due to tearing of the slab edge portion. .
[Brief description of the drawings]
FIG. 1 is a partial front view of a twin-drum continuous casting apparatus illustrating an embodiment of the present invention.
FIG. 2 is a front view taken along the line II of FIG. 1;
FIG. 3 is an enlarged sectional view showing a lower portion of FIG. 2;
FIG. 4 is a plan sectional view taken along line II-II of FIG. 2;
FIG. 5 is a plan sectional view taken along line III-III in FIG. 2;
FIG. 6 is a diagram for explaining movement of a refractory damaged portion due to an upward shift of a side weir.
FIG. 7 is a view for explaining an upward shift of a shell crimping start position by a stepped portion.
FIG. 8 is a view for explaining a reduction in seal surface width in a conventional side dam.
FIG. 9 is a diagram showing a seal surface width in the device of the present invention.
FIG. 10 is a view showing a shift amount of a side weir rising shift for each casting plate thickness.
FIG. 11 is a diagram showing a casting time extension ratio for each side weir rising shift amount.
FIG. 12 is a diagram showing a state of erosion and dissolution of refractories of a side dam.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Drum 1a ... Drum end surface 1b ... Drum stepped part 1c ... Drum seal part 1d ... Periphery of a seal part 2 ... Side dam 3 ... Refractory case 4 ... Side dam refractory 5 ... Irregular refractory 6 ... Fire resistance Brick 7: ceramic plate 8: substantially V-shaped projection 8a: inclined surface 8b at the lower end of the projection 8c: upper end 8c of the inclined surface of the lower end of the projection 8d: lower end 8d of the inclined surface at the lower end of the projection Inclined surface 8e ... Side edge 9 of the inclined surface of the projection outer surface 9 ... Stiffener 10 ... Elevating support frame 11 ... Support shaft 12 ... Pressing device 13 ... Vertical guide 14 ... Elevating drive means P ... Pool R ... Molten steel s ... Thin Obiihen g ... solidified shell p _1, p ₂ ... shell crimping starting point w _1, w ₂ ... seal surface width h _1, h ₂ ... side weirs rise stroke kp ... Doramukisu point a~b, a'~b ' D: Damaged part of the refractory on the side dam k: Drum gap

Claims (4)

In a twin-drum continuous casting apparatus in which a pair of side dams are pressed against both end surfaces of a pair of drums, a lower end surface of each of the pair of side dams is formed as an inclined surface in a chamfering direction. Continuous casting equipment. In a twin-drum continuous casting apparatus in which a pair of side weirs are pressed against both end surfaces of a pair of drums, a ring-shaped projecting seal portion is provided on an outer peripheral portion of each end surface of the pair of drums, and the pair of side weirs is provided. a protrusion provided along the contact surface between each of the seal portion, twin drum type continuous casting apparatus characterized by the outer surface formed by the inclined surface of the chamfered direction of the protrusion. In a twin-drum continuous casting apparatus in which a pair of side dams are pressed against both end surfaces of a pair of drums, a step is provided for pressing a pair of solidified shells at both end portions of the peripheral surface to both end portions of each peripheral surface of the pair of drums. A twin-drum continuous casting apparatus, comprising: a pair of side weirs; and a raising and lowering drive unit for raising the side weirs along the end surface of the drum. In a method of casting a strip slab by a twin-drum continuous casting apparatus in which a pair of side weirs are pressed against both end surfaces of a pair of drums, the peripheral end portions of each of the pair of drums are provided at both end portions of the peripheral surface. Casting is started with a stepped portion for pressing a pair of solidified shells in a state where the lower ends of the pair of side weirs are positioned within a range of 20 mm above the drum kiss point. Characterized in that each of them is raised at a speed corresponding to the wear rate.

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