JPS61209749A - Mold for continuous casting - Google Patents

Abstract

PURPOSE:To prevent the thermal expansion of a mold for continuous casting in the stage of starting drawing of an ingot and to extend the life of the mold by forming plural recessed parts to the prescribed regions of the molten metal cooling surfaces of the mold to improve the effect of cooling. CONSTITUTION:The short side casting walls 11 of the casting mold 10 are clamped between the long side casting walls 12. Plural pieces of grooves 13 extending in the drawing direction of the ingot are formed to the molten steel cooling surfaces of the walls 11. The grooves are formed to about 0.1-2.0mm width to the extent that the molten steel 4 does not cling to the groove inside. The depth thereof is made about 1.0-10.0 and the required number of the grooves is made the number corresponding to about 1.0-1.5mm expanded size when the walls 11 expand by the effect of the molten steel heat. The thermal expansion when the molten steel 4 is poured into the mold is absorbed by the decreased width of the grooves 13 and the width of the walls 11 themselves does not change.The generation of clearances between the short side and long side casting walls is therefore eliminated and the life of the mold is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a continuous casting mold capable of absorbing thermal expansion during casting of battlements, particularly short side casting walls.

[Conventional technology and its problems]

In the continuous casting mold, as shown in the plan sectional view in Fig. 7 and the longitudinal sectional view in Fig. only shown)
is sandwiched between a pair of copper long-side cast walls 2, and the long-side cast walls are tightened with a countersunk/four screw or a disc spring and a hydraulic cylinder.
Mold 3 is assembled. When molten steel 4 is injected into the mold 3 assembled in this way, it comes into contact with the molten steel cooling surface (inner surface) of the battlement 1°2 and is cooled, forming a solidified shell. this#! With a solid shell formed and containing unsolidified molten steel inside, the slab is pulled downward from the cast aS. Since this rigid 1193 is used for multiple charges, the mold 3 is repeatedly injected with molten steel 4 and subjected to thermal shock repeatedly.

In this case, since molten steel static pressure is applied to the mold 3, the disc spring 3 needs to be set so as to tighten the cylinder wall with a great force. However, the mold 3 is heated by the injection of molten steel, and the temperature drops to room temperature after casting is completed. Mold 3
Particularly, the heat applied to the mold is greatest in the vicinity of the meniscus (molten metal surface) about 100 m below the upper end of the mold, and by pouring molten steel, this meniscus, especially the vicinity of the meniscus of the short leg wall 1, tends to thermally expand.

However, since the short leg wall 1 is restrained by the disc spring and cannot expand, plastic deformation occurs due to this thermal stress. Then, when the temperature of the mold 3 drops to room temperature after the completion of casting, the short side casting wall 1 near the meniscus contracts, and a gap is created between it and the long side casting wall. Therefore, when casting the next layer, there is a problem that the molten steel ingot gets inserted into the gap.

On the other hand, in the initial stage of casting, as shown in FIG. 9, the dummy passer 5 is inserted into about the lower half of the mold, and the molten steel 4 is injected onto the dummy passer 5 from an upper nozzle. Then, due to the heat of the molten steel 4 stored on the dummy bar 5, the molten steel 4
The cylindrical wall in contact with the cylindrical wall undergoes local thermal expansion. Then, above and below this thermal expansion part, the short side casting wall 1
A gap is generated between the cast wall 2 on the long side and the cast wall 2 on the long side.

There is a problem that the molten steel injected onto the dummy pad 5 scatters and the bare metal jumps into the gap above this thermal expansion part, and the gap between the dummy pad 5 and the mold 3 exists in the gap below. There is a problem in that the sealing material and coolant that seal the space between the two may enter.

In the method of tightening the cylinder wall by adding a hot water pressure cylinder to the disc spring, the above-mentioned problems during steady casting of continuous casting can be somewhat resolved by tightening the hot water pressure cylinder, but the above-mentioned problem at the early stage of casting The above problems cannot be solved even with a four-cylinder hydraulic cylinder system.

If molten steel is inserted into the gap created between the short side casting wall and the long side casting wall due to thermal stress, breakout may occur and the copper foot wall may be damaged. Also, the insertion of this metal is a factor that reduces the life of the mold.

On the other hand, if the tightening force of the disc spring is set to a force sufficient to cancel out the static pressure of molten steel, the short side casting wall can freely expand when thermal stress is applied to the cylinder wall. However, in this case, a gap occurs between the short-side casting wall and the long-side casting wall in the relatively low-temperature portion of the lower part of the mold, resulting in the same problem as described above.

[Means for solving problems]

This invention has been made in view of the above circumstances, and by absorbing the thermal expansion of the cylindrical wall during casting, especially the short side casting wall, the short side casting wall and the long side casting wall A mold for continuous casting that can prevent gaps from forming between the molten steel and the molten metal, prevent breakouts from occurring due to molten steel intruding into the gaps, and prevent damage to the cylindrical wall, extending the life of the mold. The purpose is to provide

A continuous casting mold according to the present invention is a continuous casting mold in which a molten metal is cooled through a molten metal cooling surface and a slab in which a solidified shell has been formed is continuously pulled out. It is characterized by having a recess formed therein.

〔Example〕

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a horizontal sectional view of a continuous casting mold according to a first embodiment of the present invention, FIG. 2 is a front view of its molten steel cooling surface, and FIG. 3 is a side sectional view thereof. The short side casting wall 11 of the mold 1O is sandwiched between the long side casting wall 12, and is tightened by appropriate means such as a disc spring (not shown). It is tightened between the side cast walls 12. The cylinder wall xrtzx is made of copper or a copper alloy. The molten steel cooling surface of the short-side cylinder wall 11 (the surface in contact with the WI steel 4) has a plurality of grooves 13 (11 grooves in the illustrated example) extending in the direction in which the slab is pulled out (vertically downward). ) is formed. The width of this groove is set to such an extent that the molten steel 4 does not get entangled in the groove, for example, 0.1 to 2.0 m. The required number of grooves 13 is such that the total width thereof corresponds to an expansion dimension of 1.0 to 1.5 m when the short side cast wall 1'1 thermally expands in the width direction due to heat of molten steel. is the number of The depth of the groove 13 is suitably 1.0 to 10.0 m in order to absorb thermal expansion.

The surface of the short side casting wall 11 opposite to the molten steel cooling surface has #
Cooling grooves 14 are formed in the I wall, and a pack frame 15 is disposed on this surface, so that the pack frame I5 supports the short side cast wall II from behind. There is.

In the continuous casting mold configured as described above, when molten steel 4 is injected into the casting chamber at the start of casting, the part of the battlement directly above the dummy pavers (not shown), especially the part of the short side casting wall, absorbs the heat of the molten steel. It tries to thermally expand. However, the thermal expansion due to the heat of molten steel is absorbed by the shortening of the width of the groove 13, and the width of the short side cast wall 11 itself does not change.

After continuous casting shifts to steady casting, the temperature of the battlement near the meniscus about 100 degrees below the upper end of the mold becomes the highest. As a result, the battlement part of this part, especially the short side cast wall part, tends to thermally expand, but the thermal expansion is absorbed by the shortening of the width of the groove 130, and the short side of this part The width dimension of the side cast wall 11 itself does not change. In this way, in this invention, local thermal expansion is applied to the molten steel cooling surface of the battlement 11, but this thermal expansion is absorbed by the plurality of grooves 13 formed in the molten steel cooling surface, and the battlement wall The width dimension of 11 always remains constant.

Next, regarding other embodiments of the present invention, FIGS.
Explain the breathing with reference to the diagram. In each of the embodiments, the form of the recess formed in the molten steel cooling surface of the battlement is variously changed. First, in FIG. 4, a plurality of relatively short grooves 16 are formed in the molten steel cooling surface, each extending in the direction in which the casting edge is drawn out and in a direction perpendicular thereto. Further, in the embodiment shown in FIG. 5, a plurality of grooves 17 are formed on the mesh so as to intersect with each other, and the grooves 17 are inclined with respect to the drawing direction of the cast side. In the embodiment shown in FIG. 6, a large number of holes 18 are formed in the molten steel cooling surface. As described above, various modifications can be considered as one form of threat formation.

These (in both embodiments, even if local thermal stress is applied to the molten steel cooling surface of the battlement, it will be absorbed by the short groove I6, the intersecting groove 12, and the large number of holes 18, and the width of the battlement 11 will change. There isn't.

〔Effect of the invention〕

According to this invention, since a plurality of grooves or the like extending in the drawing direction of the casting side are formed in a predetermined area of the molten steel cooling surface of the battlement, particularly on the molten steel cooling surface of the short side casting wall, Even if a larger thermal expansion is applied to the battlement wall near the dummy pad at the start of edge drawing or the battlement wall near the meniscus during steady casting compared to other parts, the change in the size of the recess will cause the expansion of these areas. Thermal expansion is absorbed and the width of the parapet itself does not change, so there is no gap between the short side casting wall and the long side casting wall. This prevents damage to the parapet wall in the event of a breakout caused by insertion into a gap, extending the life of the mold.

[Brief explanation of drawings]

FIG. 1 is a horizontal sectional view of a continuous casting mold according to a first embodiment of the present invention, FIG. 2 is a front view of its molten steel cooling surface, FIG. 3 is a side sectional view thereof, and FIGS. FIG. 6 is a front view of the molten steel cooling surface of a continuous casting mold according to another embodiment of the present invention, FIG. 7 is a plan view showing a conventional continuous casting mold, and FIG. 8 is a longitudinal sectional view thereof. , FIG. 9 is a longitudinal cross-sectional view of the same, showing the vicinity of the dummy pad. 10... Mold, 11... Short side casting wall, 12... Long side casting wall, 13.16.17... Groove, 18... Hole.

Claims (4)

[Claims] (1) In a continuous casting mold in which the molten metal is cooled through the molten metal cooling surface and a slab with a solidified shell formed thereon is continuously pulled out, a plurality of recesses are formed in a predetermined area of the molten metal cooling surface. A continuous casting mold featuring: (2) The continuous casting mold according to claim 1, wherein the recess is a groove extending in the direction in which the slab is pulled out. (3) The continuous casting mold according to claim 1, wherein the recess is a small hole. (4) The molten steel cooling surface has a cooling surface of a pair of long-side casting walls and a cooling surface of a pair of short-side casting walls spanning between the long-side casting walls, and The continuous casting mold according to claim 1, wherein the region is a cooling surface of the short side casting wall.