JPH0120941B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a mold device for horizontal continuous casting,
Specifically, the present invention relates to a molding device in which a mold is divided and installed corresponding to a flat surface formed on a break ring. This is used in the field of continuous casting of molten steel in a horizontal state.

[Prior art]

In equipment that continuously casts billets, etc. by flowing molten steel stored in a tundish nozzle through a tundish nozzle and cooling it as it passes through a horizontally arranged mold, a break ring is installed on the inlet side of the mold. It is being The break ring is used to define the solidification start point of molten steel in the mold and to promote separation of the shell, and is made of a dense, non-porous material that is difficult for molten steel to adhere to. It is a ceramic material, such as boron nitride, and has an extremely low coefficient of thermal expansion. On the other hand, molds are made of copper or its alloys, which have high thermal conductivity because it is necessary to cool the molten steel, and therefore have a large coefficient of thermal expansion. the result,
There is a difference in the amount of thermal expansion between the break ring and the break ring provided by fitting into the mold, which reduces the degree of adhesion between the break ring and the mold, and impedes the sealing performance of molten steel.

In order to solve this problem, as shown in Figure 5,
In some cases, the entrance side of the mold 31 and the mold side of the break ring 32 are formed into a tapered shape, and the break ring 32 is fitted into the mold 31. According to this, even if the degree of adhesion decreases due to a difference in the amount of thermal expansion, the sealing of the molten steel can be ensured again by moving the mold 31 along its axis in the break ring direction.

By the way, although the break ring exhibits the above-mentioned function, it is subject to severe wear due to erosion of the solidified shell formed on the end face. Particularly, on the side where the molten steel starts to solidify, the area N shown by hatching is particularly noticeable.
is consumed, and molten steel digs into the gap between it and the mold. As a result, when the slab is drawn, it breaks, resulting in a defective product, and the break ring can no longer be used. At present, the service life is about 4 to 5 hours at most, and the service life limit of the break ring greatly controls the operating efficiency of the continuous casting equipment. It should be noted that extremely high precision is required for manufacturing the tapered surface, which has the disadvantage that machining the surface in the break ring is not easy and is expensive. Incidentally, there is a type of break ring that does not have a tapered surface and is applied to the end surface of the mold, but it has the problem that similar wear and the resulting roughening of the solidification start point cannot be avoided.

[Purpose of the invention]

The present invention was made in view of the above-mentioned problems, and its purpose is to extend the service life of consumable break rings and improve the quality of cast products, as well as to manufacture break rings that require high-grade molding and processing. It is an object of the present invention to provide a mold device for horizontal continuous casting that can easily perform horizontal continuous casting.

[Structure of the invention]

The features of the horizontal continuous casting mold apparatus of the present invention will be explained with reference to FIG. The molds are installed separately, each mold 2A, 2B...
is the mold fixing frame 1 installed behind it.
3, and the entire mold is provided with an elastic support member 20 for holding the break ring 6 under pressure. In addition to the above-described configuration, the second invention is that all or part of the mold is disposed so as to be thermally expandable in the circumferential direction of the break ring 6.

〔Example〕

The present invention will be explained in detail below based on examples thereof. FIG. 2 is a cross-sectional view of the molding device installed so that the mold 2 is connected to the tundish nozzle 1, and the molten steel 4 in the tundish nozzle 3
is cooled in the mold to form the slab 5. In this example, a connecting ring 7 is provided on the end face of the mold 2 to press a non-porous break ring 6 in the axial direction of the mold and to ensure a seal with the nozzle 1. It is integrated into the mold 2 with bolts 9 and the like. The connecting ring 7 is made of a porous and inexpensive ceramic material, and in order to seal with the nozzle member 10, an amorphous refractory material 11 is used to ensure close contact.

The break ring 6 itself consists of a flange portion 6a and a cylindrical portion 6b following the flange portion 6a, and a flat surface 12 extending in the axial direction of the mold 2 is provided on the outer surface of the cylindrical portion that has a wear margin.
is formed. If the cylindrical portion 6b is rectangular, this surface has four flat surfaces as shown in FIG.
A mold 2 is installed in a divided manner corresponding to each surface, and each divided mold 2A, 2B, . A mold fixing frame 13 is provided behind each mold, and the mold 2
It is supported via a header 14 that supplies and discharges cooling water from A, 2B, and so on. The headers are provided at two locations in the axial direction of the mold 2, at the front and rear for each divided mold (see FIG. 2), and have a watertight structure with the mold via an O-ring 15. Note that the split mold is formed longer than one side of the break ring 6,
A recess 16 provided on the outer side of one end of each
is engaged with a protrusion 26 provided on the header 14. This not only allows the split molds 2A, 2B, . . . It's for a reason. Therefore, in this example, the right end inner surface P of the split mold is arranged in a swastika-like manner such that it contacts the left end surface Q of the mold adjacent to it on the right side.

The mold fixing frame 1 is attached to the header 14 that supports such split molds 2A, 2B...
Support protrusions 17 are provided on both sides for attachment to 3. A bolt 18 is inserted through one of the protrusions, and a nut 19 is attached to define the amount by which the header 14 is protruded toward the brake ring, and to fix it. A spring 20 serving as a resilient support member is interposed in the other protrusion, so that the fully divided mold exhibits the effect of holding the break ring 6 under pressure. Note that the tandate nozzle is made of porous refractory material, and if it is too close to the mold, it will cool and solidify on its inner surface, inhibiting casting, so a non-porous connecting ring 7 is used in the middle. There is. However, the connecting ring 7 may be omitted if it is possible to make close contact with the monolithic refractory material and to seal the connection portion with the tundish.

According to the embodiment having such a configuration, continuous operation can be performed while allowing the break ring 6 to wear out as described below.

First, the work of attaching the break ring 6 to the mold 2 will be explained. In Figure 1, header 1
The amount of protrusion of 4A and 14B is determined, and the rotation of the bolt 18 is fixed with a nut 19. The break ring 6 is placed so that the flat surfaces 12A, 12B of the cylindrical portion 6b are along the inner surfaces of the split molds 2A, 2B supported by the two headers. Then, the split molds 2C and 2D facing the other flat surfaces are made to protrude in the direction of the brake ring 6, and the respective headers 14 are
Fix the bolts 18 of C and 14D. Each header 1
4, the inner surfaces of the split molds 2A, 2B, . . . come into contact with the outer surface of the break ring 6, and force is exerted on each other to clamp the break ring. Therefore, the break ring 6 is supported approximately at the center of the mold fixing frame 13.

In this state, as shown in FIG. 2, the connecting ring 7 is brought into contact with the flange portion 6a of the break ring 6,
When the connecting ring 7 is fixed by the ring presser 8, the tundish nozzle 1 is brought into contact with the unshaped refractory material 11 in between, and a leak-free connection between the tundish and the molding device is achieved.

The molten steel 4 in the tundish 3 is exposed to the refractory wall 21.
When the molten steel flows out through the nozzle 1 provided in the mold 2, the mold 2 is filled with the molten steel via the connection ring 7 and the break ring 6. A cooling water passage 22 is formed in the mold for each divided mold 2A, 2B, etc., and while the cooling water distributed from the header 14 near the tundish is flowing toward the other header, the molten steel in the mold is cooled. and begins to coagulate. Since the break ring 6 is non-porous, there is no solidification and adhesion of molten steel, and the contact position between the outer end of the break ring and the mold 2 is defined as the solidification start point M of the molten steel, and the molten steel gradually solidifies from the part near the mold. . By intermittently pulling the solidified part of the slab 5 with a stroke L, a continuous casting is obtained. It should be noted that the solidification of the portion near the axis of the mold is delayed, and while a wave-shaped solidified shell is formed for each stroke as shown in the figure, it becomes smaller as it goes in the drawing direction R.

In such a casting operation, the break ring 6 and the split mold 2A receive heat from the molten steel.
2B... each expands. The mold 2 is made of copper or the like, and a temperature increase of 300°C causes a thermal expansion of 1.62 mm in a length of 300 mm. On the other hand, break ring 6 made of boron nitride etc. has a diameter of 300mm with a temperature change of 800℃.
The amount of expansion is 0.24mm in length. In addition, the former is heated to 300℃
This is because it is cooled and the temperature rise is small. Therefore, the amount of thermal expansion of both is 1
A difference of more than mm will occur, but if the split molds 2A, 2B... are arranged in a swastika pattern as shown in FIG. can be released to Of course, the split molds will not interfere with each other, and there will be no adverse effects such as damaging the seal with the brake ring. Incidentally, the mold 2 expands as it approaches the inner direction of the brake ring, but the thickness of the mold is, for example, about 30 mm, and the adverse effects of expansion can be almost ignored.

When casting is performed with the break ring 6 and the mold 2 maintained in close contact, the vicinity of the solidification start point M of the break ring 6 is consumed due to the pushing back of the slab and the flow of molten steel. Although the cylindrical portion 6b will be slightly reduced in size, the length is determined in advance with consideration for wear and tear, so the function as a break ring will not deteriorate. Of course, since the cooling length of the mold 2 is estimated in advance, there is no problem in solidifying the molten steel. And the cylindrical part 6b
The flat surface 12 in each split mold 2A, 2B
Since it is maintained in close contact with the mold, molten steel will not get stuck between it and the mold, and the slab will not break when pulled. There is no problem with casting without impairing the sealing performance, just by moving the solidification start point slightly closer to the nozzle. Therefore, if the consumable amount is increased by three to four times the conventional amount by ensuring a large consumable allowance, the service life can be significantly extended. The break ring 6 can be easily replaced by loosening the bolts 18 that fix the header 14 behind each of the split molds 2A, 2B, . . . .

FIG. 3 shows a different embodiment, which is an application example where the break ring has a horizontally elongated shape. In this example, the split molds 22A and 22C along the long sides are made to be thermally expandable, and the other two split molds 22B and 22D are made to have the same dimensions as the short sides of the break ring 23.
It is arranged so as to be sandwiched between A and 22C. One of the opposing split molds is fixed to the mold fixing frame 13, and the other is biased by a spring 20, which is a resilient support member, and the break ring 23 is clamped by this force.

In this example as well, since the flat surface 24 formed on the cylindrical portion of the break ring 23 can be pressed, even if the end of the break ring wears out, it is possible to ensure close contact with the mold 22, thereby preventing slight wear of the break ring. You can continue casting even if there is a problem. It should be noted that it is not easy to manufacture a large break ring made of non-porous ceramic due to manufacturing problems. Therefore, a split body as shown by the broken line in the figure may be adopted, but as long as it is processed to ensure close contact on the adjacent surfaces, there will be no problem with the pressing action of the resilient support member. Does not occur. Further, since the molten steel after flowing through the break ring 23 joins together in the mold 22, various shapes such as a circle or a rectangle can be selected for the several flow holes 25 provided in the break ring.

FIG. 4 shows another embodiment, in which the break ring 6 of the first embodiment is further improved.
In the break ring described above, each mold 2A, 2
Since the pressure for sealing between B... and the pressure for sealing between break ring 6 and mold 2 are the same, the pressure is greater for either break ring 6 or mold 2, whichever has greater rigidity. It is easy to receive. In addition, the mold 2 expands inward toward the break ring, and even if the mold is thin and the expansion causes little damage, there is thermal expansion in the thickness direction of the mold 2 itself. The seal may deteriorate. In reality, the problem is solved by maintaining the dimensional accuracy of the break ring's outer cylinder and relying on the elastic and plastic deformation of the break ring itself.
However, according to the example in Fig. 4, the brake ring 6
A fiber layer 2 of, for example, C, BN, Si, etc. is placed on the outer cylinder surface of the
Since the layer 8 is bonded with an inorganic adhesive, the layer can be compressed and deformed during mold assembly to improve the sealing performance between the mold and the break ring.

Such a break ring has the advantage that it can be used without requiring much dimensional accuracy. Furthermore, it is easy and convenient to use hard ceramics such as silicon nitride and sialon with low elastic and plastic deformability as the break ring.

In addition, in the above-mentioned embodiment, the shape of the slab was explained as an example of a rectangular slab, but depending on the arrangement of the split molds, the present invention can also be applied when casting a slab with a special cross section such as a beam blank. Can be applied.

〔Effect of the invention〕

As can be seen from the description of the embodiments above, the present invention has the following features:
A flat surface is formed on the outer surface of the break ring, and the split mold corresponding to the flat surface is supported by a mold fixing frame provided behind it, so that the cylindrical portion forming the flat surface is brought into close contact with the split mold. Can hold brake rings. As a result, the cylindrical portion can be made longer to ensure sufficient wear and tear, and the service life of the break ring can be increased. In addition, in other inventions, all or part of the split mold is disposed so that it can thermally expand in the direction of the side of the break ring, which may cause a difference in the amount of thermal expansion and hinder the close contact with the mold. This will be avoided. Therefore, problems related to break rings in horizontal continuous casting are solved, and great practical effects are achieved.

[Brief explanation of drawings]

Fig. 1 is a sectional view of a horizontal continuous casting mold device of the present invention, Fig. 2 is a longitudinal sectional view taken along the line - - of Fig. 1, Fig. 3 is a sectional view of a different embodiment, and Fig. 4 is a break ring. In a different embodiment, FIG. 5 is a conventional diagram showing a state in which a brake ring is attached. 1... Tandate nozzle, 2, 22... Mold, 2A, 2B..., 22A, 22B... Division mold, 6, 23... Break ring, 12, 24...
Flat surface, 13... Mold fixing frame, 20... Resilient support member (spring).

Claims (1)

[Scope of Claims] 1. A horizontal continuous casting mold device in which a break ring is provided in a mold communicating with a tundish nozzle, wherein a plurality of flat surfaces extending in the axial direction of the mold are formed on the outer surface of the break ring. The molds are divided and installed corresponding to each flat surface, each mold is supported by a mold fixing frame provided behind it, and all molds are equipped with resilient support members to hold the break ring under pressure. A mold device for horizontal continuous casting, which is characterized by: 2. In a horizontal continuous casting mold device in which a break ring is provided in a mold communicating with a tundish nozzle, a plurality of flat surfaces extending in the axial direction of the mold are formed on the outer surface of the break ring, and each of the flat surfaces The molds are divided and installed in accordance with A mold device for horizontal continuous casting, characterized in that a resilient support member is provided for the mold to hold the break ring under pressure.