JPS60170566A - Method and device for producing longitudinally short steel ingot - Google Patents

Abstract

PURPOSE:To provide a steel ingot having no defects such as blow holes, central segregation, etc. by providing a pouring spout into a casting mold, casting a molten steel from a tundish through a nozzle and the pouring spout into the mold and moving horizontally the mold in a specified direction while adjusting the molten metal surface in the mold. CONSTITUTION:The molten steel in a ladle 1 is received in a tundish 2 and is cast through a nozzle 3 and a pouring spout 4 into a casting mold 7. When the molten metal surface attains a prescribed height, a heat insulating material 14 is supplied onto the molten metal surface and the mold 7 is horizontally and gradually moved in a specified direction. The opening degree of the nozzle 3 is adjusted at the same time to control the rate of pouring, thereby maintaining the molten metal surface at a specified height. On the other hand, water is supplied to water cooling nozzles 12 below a molding board 8 to cool the board 8. When the length of the cast steel ingot attains a prescribed length, the movement of the mold 7 is stopped and at the same time the nozzle 3 is closed to end casting.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to a method and apparatus for manufacturing a vertically short steel ingot without center segregation by solidifying molten steel in one direction from the bottom surface.

Conventional technology and its problems The ratio of the horizontal short side (D) to the height H) of the steel ingot (
Steel ingots with H/D ) of 1 or less (hereinafter referred to as "vertical and short steel ingots")
By effectively performing unidirectional solidification from the bottom upward, the problem of segregation and hollow defects, which had been a major problem in the past, has been improved, and the internal quality of the steel ingot has been improved, and the yield has increased. Many proposals have been made to realize such substantial unidirectional solidification, as it is also expected to improve the solidification, but the reality is that there is still much room for improvement. Especially the bottom of the mold (or surface plate)
The area of the nozzle is large, and the molten metal that flows out of the nozzle comes into contact with the bottom and flows while losing heat, forming a double skin in the part away from the nozzle. Also, because the rate of rise of the molten metal level during the casting process is very slow, a solidified shell is formed on the surface, the weak points of which break and molten steel gushes out from within, and the molten metal covers the solidified layer. Coagulation progresses under the most unfavorable conditions. As a method to solve such problems, for example, Japanese Patent Application Laid-Open No. 54-81125 discloses a method in which a part of the mold is partitioned, molten metal is poured into the partition, and then the partition (weir) is gradually moved. A method has been proposed for enlarging the area to be filled.

However, since the enema nozzle to the mold is fixed in place, there is a risk that solidification will progress and block the nozzle hole.
Uniform hot water supply becomes difficult. In addition, when hot water is supplied through a nozzle, the flow of molten steel becomes complicated, resulting in a double skin on the bottom, and the surface is not smooth. In addition, a complex molten steel flow solidifies unevenly in parts, so when stress due to solidification shrinkage is applied to the slab, cracks occur in areas where solidification is slow, resulting in fatal defects. Furthermore, since the position of the nozzle remains unchanged, there is a risk of shallow pot formation due to floating.

OBJECTS OF THE INVENTION It is an object of the present invention to solve these problems and provide an effective method and apparatus for manufacturing vertical and short steel ingots.

A method for manufacturing a vertically short steel ingot according to the present invention is a method for manufacturing a vertically short steel ingot by performing unidirectional solidification from the bottom surface, in which a water heater is provided in a mold, and molten steel is passed through a tundish and a nozzle into the water heater. The molten metal is poured into the mold, and the mold is moved horizontally in a certain direction while adjusting the level of the molten metal in the mold.

That is, the present invention is basically a method of casting in a fixed position while moving the mold horizontally, and a flow of molten steel is leveled across the width of the mold via a water heater installed in the mold. This is a method of supplying.

In the case of this method, the mold is moved horizontally in a certain direction, and the hot water supply position changes relatively, so there is no risk that the hot water supply port of the hot water supply trough will become blocked due to the progress of solidification.
Uniform hot water supply becomes possible. In addition, since the molten steel flows into the mold in a uniform flow across the width of the mold via the water heater, the bottom surface does not have double skin and the surface texture is smooth. In addition, because the solidification is uniform, cracks do not occur even when stress due to solidification shrinkage is applied to the slab, and a slab of good quality with extremely few defects such as blowholes and center segregation can be obtained.

Furthermore, even if the water heater is fixed, the position of the hot water changes as the mold moves, so damage to the inner wall of the mold and the top surface of the surface plate is significantly reduced.

In addition, an apparatus for producing vertical and short steel ingots for carrying out the method of the present invention includes a water heater provided in a horizontally movable mold, and a tundish installed above the mold and the water heater connected to a nozzle. The water heater is connected to the tundish, and is characterized by having a weir integrally constructed with the tundish on the rear surface of the water heater.

Here, the mold is placed on the hill of a movable surface plate and is provided so as to move integrally with the surface plate in the longitudinal direction. As a moving mechanism, for example, a method of attaching wheels to a surface plate and driving it on a V-ru can be used (hereinafter referred to as blank space). The water heater and weir have a height that is almost flush with the top surface of the mold, and are arranged in the width direction of the mold so that they slide on the long side inner wall of the mold and the top surface of the surface plate. The structure is such that molten steel is supplied into the mold from an outlet provided in the width direction of the mold on the front surface.

Molten steel is supplied to the water heater via a nozzle from a tundish placed above the mold. The weir is also fixed to the tundish via a suitable member.

According to the device having the above structure, molten steel flows from the tundish through the nozzle into the water heater in the mold, and flows into the mold through the outlet provided in the width direction of the mold.

That is, since the molten steel once accumulates in the hot water supply gutter and flows out horizontally from the front of the water heater, the flow of the molten steel is gentler and smoother than in the conventional method of directly casting from a tundish nozzle. In addition, since this method moves the mold horizontally while pouring molten steel, the inner wall of the mold and surface plate surface (
Damage to the bottom of the mold is significantly reduced. Furthermore, since the water heater and weir are integrated with the weir dish, floating of molten steel in the mold is prevented and there is no risk of steel leakage.

In addition, since the device of the present invention is relatively simple in structure, it is possible to
It is not expensive and is easy to operate.

Next, an embodiment of the present invention will be explained based on the drawings.

In Figure 1, (1) is a ladle, (2) is a tundish, (3) is a tandish nozzle, and (4) is a feeder! 1!
, (51 is the weir fixing member, (6) is the weir, (7) is the mold, (
8) shows each surface plate. The water heater (41J/i) has an outlet (4-1') drilled in the mold width direction on the front surface,
and a tundish nozzle (3) provided through the top surface.
It has an integrated configuration. Further, the weir (6) is fixed in contact with the back surface of the water heater (4) by a fixing member (5) K provided vertically on the lower surface of the tundish (2).

The surface plate (8) on which the mold (7) is placed is movably installed on a rail FVF91 laid in the longitudinal direction via wheels (101), and a drive device such as a motor or cylinder (not shown). The mechanism is driven by K, and the tanditsh (2) is installed at the desired height by the support αυ so as to straddle the mold travel line.

Note that a water cooling nozzle (2) is provided on the lower surface of the surface plate (8). (131 is the ear for cutting.

When manufacturing vertical and short steel ingots using the above equipment, ladle (1)
Once the molten steel inside is received by the tundish (2), and after it has been sufficiently accumulated in the tundish, the molten steel is transferred to the tundish nozzle (3).
, hot water is supplied through the water heater (4). At this time, the molten steel is
As shown in the figure, the inner walls of the short and long sides of the mold and the water heater (
The water heater outlet (4-
1).

In this way, hot water is supplied to the initially set mold space, and when the hot water level reaches a predetermined height, a heat insulating material (for example, rice husk) is supplied on top of the hot water surface, and the mold (7) is gradually raised. move it to Thereafter, the amount of hot water supplied is controlled by adjusting the opening of the tundish nozzle/l/(3) so as to maintain the hot water level at a constant height.

Additionally, as the mold moves, a heat insulating material is supplied onto the newly formed surface of the molten metal to prevent cooling from the surface. On the other hand, in order to promote unidirectional solidification from the bottom, water is supplied to the bottom of the surface plate (8) through water cooling nozzles (121 km), and the surface plate is cooled by water spray.

After that, when the length of the steel ingot reaches a predetermined length, the movement of the mold is stopped and at the same time, the tundish nozzle (3) is closed to complete the casting. Thereafter, the molten steel in the mold is left until solidification is completed, and after confirming complete solidification, the weir (6) is removed, and the mold is further removed using the lug αJ.

The steel ingot obtained by K in this manner has extremely few defects such as blowholes and center segregation because the molten steel flow during pouring solidifies uniformly as described above.

An example in which a vertical and short steel ingot was actually produced using the above-mentioned apparatus will be described below.

Example Molten steel having the components shown in Table 1 (1,560°C) melted in a converter was melted into a steel ingot with a width of 10,100 m, a length of 3,000 m, and a height of 3,000 m, using a vertical and short steel ingot manufacturing device with the equipment specifications shown in Table 2. 200
Manufactured a slab of praise.

Table 1 Composition of Molten Steel (%) Table 2 Equipment Specifications In this example, before starting casting, the hot water supply gutter was set at a position of 300111111 from the short side of the tip of the mold, and the injection of molten steel was started. When the height of the molten steel in the mold reached 200+ m, the mold started moving at a speed of 0.6 m1IIIiI.

Thereafter, the opening of the tundish nozzle was adjusted to maintain the melt level at 2001111I, and casting was continued. Also, water was supplied to the water cooling nozzle at the same time as the casting started, and water supply was continued for 50 minutes. Roasted rice husks were poured into the medium temperature part of the casting to a thickness of about 50 pieces.

Four minutes and 30 seconds after starting the movement of the mold, the tundish nozzle was closed, and at the same time, the movement of the mold was stopped. The molten steel in the mold was left to stand for about 50 minutes, and after confirming complete solidification, the weir was removed and the mold was removed using ears.

The slab obtained in this way (width 1000 cm x length 3
000mm x height 200mm
00en was used for 5 times, and the remaining half was used for 10++ll+solvent. When the slab thus treated was divided into 11 equal parts at equal intervals in the longitudinal direction and a macroscopic test and puntophytoedge were performed on the cross sections, no defects such as blowholes or center segregation were observed, and the crystal orientation was along the longitudinal direction of the slab. 10 at both ends of the direction
It extended in the lateral direction by about 0 mg, but on other surfaces, it extended in one direction from the bottom surface to the top surface.

In addition, in the Hot Scarfing 5++I+I+ section, there was some segregation in the 1st or 2nd cabinet directly below the north face, but in the Hot Scarfing 10 vote section, no segregation was observed.

For comparison, when molten steel with the same composition as described above was cast using a conventional device that produces vertical and short steel ingots by moving a weir that was slidably installed in the mold, as solidification progressed, As a result, the tundish nozzle (nozzle hole 30φ) became almost clogged, making uniform hot water supply difficult. When hot scarfing was performed on a cast slab with the same dimensions as above and the internal quality was examined, blowholes were confirmed, and furthermore, segregation was observed in the hot scarfing area. Additionally, the bottom of the mold was severely damaged.

As is clear from the above examples, according to the present invention, a long and short steel ingot of good quality can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a schematic perspective view showing an apparatus according to an embodiment of the present invention, and FIG. 2 is a schematic longitudinal sectional side view showing a state in the middle of casting by the same apparatus. 1...Ladle, 2...Tanditshu, 3...
・Tanditshu nozzle, 4...Hot water gutter, 4-1・
...Outlet, 5...Fixing member, 6...Weir, 7
... Mold, 8 ... Surface plate, 9 ... Rail, 1
0...wheel, 11...post. Figure 1 Figure 2

Claims (1)

[Claims] l In a method for manufacturing vertical and short steel ingots by unidirectional solidification from the bottom surface, a hot water supply gutter is provided in the mold, and the molten steel is passed through a tundish and a nozzle into the hot water feed gutter! 7. A method for producing a vertically short steel ingot, which is characterized by casting into a mold and moving the mold horizontally in a fixed direction while adjusting the molten metal level in the mold. 2. An apparatus for producing vertical and short steel ingots by unidirectional solidification from the bottom surface, characterized in that a hot water supply gutter is provided in a horizontally movable mold, and is provided astride above the mold. Lump manufacturing equipment.