JPH11267799A - Production of rapidly cooled and solidified thin sheet and apparatus therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To uniformize the solidification and the shrinkage at the time of solidifying a cast slab, to prevent the development of crack on the surface of the cast slab and to obtain the cast slab of the improved quality, at the time of producing the cast slab for thin sheet in a rapidly cooled and solidified thin sheet producing device. SOLUTION: At the time of producing the cast slab 5 for metallic thin sheet by supplying molten metal 3 into a gap between one pair of cooling type casting drums 1 mutually rotated in the reverse direction, and allowing the molten metal 3 to contact with the surfaces of the casting rolls 1 and cooling to form the solidified shell, many fine recessed parts 13 are formed on the surfaces of the casting drums 1, and metallic powder 14 is filled in the recessed parts 13. The metallic powder 14 is brought into contact with the molten metal 3 by rotating the casting drums 1 and sintered-combined with the solidified shell of the molten metal 3 to release the heat strain in the cast slab 5 by spike-effect of the sintered metallic powder.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the prevention of slab surface cracking in a rapidly solidified thin plate manufacturing apparatus for supplying molten metal between a pair of rotating casting drums and cooling the molten metal to produce a slab of a thin metal plate. A method and an apparatus therefor.

[0002]

2. Description of the Related Art FIG. 6 is a schematic side view showing a structure of a general rapid solidification sheet manufacturing apparatus. In FIG. 6, reference numerals 1 and 1 denote a pair of water-cooled casting drums which are driven to rotate in opposite directions (directions of arrows in the drawing), 8 denotes a tundish in which molten metal (hereinafter referred to as molten steel) 3 is accommodated,
Is a nozzle provided at the lower part of the tundish 8, 2,
2 is a side dam provided below the nozzle 4,
The molten steel 3 in the tundish 8 is supplied from the nozzle 4 into the side dam 2, and the molten steel 3 in the side dam 2 is brought into contact with the surface of the casting drum and cooled to form a solidification cell 9. 5 is to be cast.

The side dams 2 and 2 are made of a fire-resistant and heat-insulating material. The side dams 2 and 2 store the molten steel 3 between the casting drums 1 and 1 and prevent leakage to the outside.
Are press-contacted to both ends. Guide rolls 6, 6a and a pinch roll 7 are provided downstream of the casting drums 1, 1, and a slab 5 cast from the casting drums 1, 1 is provided.
Is pulled out at a predetermined speed by the pinch roll 7 through the guide rolls 6 and 6a, and is sent to the next step.

[0004]

In the above-mentioned conventional rapidly solidified thin plate manufacturing apparatus, depending on the type of metal (steel) to be cast, a step of cooling and solidifying from a molten state with a casting drum to produce a solidified cell. In some cases, the coagulation is not uniform. In such a conventional case, in such a case, there is a problem that shrinkage of the slab after solidification becomes non-uniform, so that fine cracks are generated on the surface of the slab.

SUMMARY OF THE INVENTION An object of the present invention is to provide an apparatus for manufacturing a rapidly solidified thin plate, in which a slab of a thin plate is manufactured, in which the solidification and shrinkage during the solidification of the slab are made uniform to prevent cracks on the slab surface. Another object of the present invention is to obtain a slab with improved quality.

[0006]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems, and a first invention is to supply molten metal between a pair of cooling-type casting drums rotating in opposite directions to each other. The molten metal is brought into contact with the surface of the drum and cooled to form a solidified shell, and when casting a thin metal slab, a large number of fine recesses are formed on the surface of the casting drum. A method for producing a rapidly solidified thin plate, characterized in that a powder is filled and the metal powder is brought into contact with the molten metal by rotation of the casting drum to sinter and bond with a solidified shell of the molten metal.

A second invention relates to an apparatus for carrying out the first invention, wherein molten metal is brought into contact between a pair of cooling casting drums rotating in opposite directions to each other to cool the solidified drum. In a rapid solidification sheet manufacturing apparatus for forming a shell and casting a slab of a metal sheet, the casting drum has a number of fine recesses engraved on a surface thereof, and a metal powder for sintering is formed in the recess. It is characterized by comprising metal powder supply means for supplying, and metal powder removal means for removing sintered metal powder remaining in the recess.

According to the invention, the metal powder filled in the recesses on the surfaces of the casting rolls is brought into contact with the molten metal with the rotation of the pair of casting rolls, whereby the metal powder is sintered and joined to the solidification cell of the molten metal, The metal powder sintered on the surface of the solidification cell generates a spike effect and finely constrains the solidification cell, releasing the thermal strain associated with the solidification shrinkage of the solidification cell and reducing the thermal stress . Thereby, the solidification of the slab is made uniform, and the occurrence of fine cracks on the surface of the slab can be prevented.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to FIGS. FIG. 1 is a side view showing the structure of a rapidly solidified thin plate manufacturing apparatus according to an embodiment of the present invention, and FIG.
FIG. 3 is an enlarged partial cross-sectional view of the outer peripheral portion of the casting drum, FIG. 3 is a partial cross-sectional view showing a modified example of the outer peripheral portion, FIG. 4 is a view as viewed in the direction of the arrow Z in FIG. 2, and FIG.

In FIG. 1, reference numerals 1 and 1 denote a pair of water-cooled casting drums which are driven to rotate in opposite directions (in the direction of the arrow in the figure), and 8 denotes a tundish in which molten metal (hereinafter referred to as molten steel) 3 is accommodated. Numerals are nozzles provided below the tundish 8, and 2 and 2 are side dams provided below the nozzle 4.

The side dams 2 and 2 are made of a fire-resistant and heat-insulating material, and store the molten steel 3 between the casting drums 1 and 1 and prevent the steel drum 3 from leaking outside.
Are press-contacted to both ends. Guide rolls 6 and 6a are provided downstream of the casting drums 1 and 1 to guide a slab 5 cast from the casting drums 1 and 1, and 7 are provided downstream of the guy rolls and guide the slab 5 Pinch roll to pull out. The above configuration is the same as the conventional one shown in FIG.

In the present invention, the following points are improved. A plurality of circular recesses 13 are formed in the outer peripheral surface 1a of the casting drums 1, 1. The concave portion 13 has a rectangular cross section as shown in FIG. 2 and a circular surface shape as shown in FIG. 4, and is formed in a large number on the outer peripheral surface 1a at a required pitch. The recess 13 has a depth H and a diameter D of about 100 μm and D = 500 μm.
About m is a preferable example.

3 (a) and 3 (b) show a modified example of the concave portion 13, wherein FIG.
(B) shows a concave section 13 having a semicircular cross section.

Reference numerals 11 and 11 denote metal powder supply devices provided near the outer periphery of the casting drums 1 and 1, respectively, and a metal powder 14 such as iron powder is stored in a box. The material, particle size and the like of the metal powder 14 are appropriately selected according to the steel type of the cast slab 5 to be cast. 12 is a rotating brush, 12a
Is a shaft, which is provided in a pair below the metal powder supply device 11 so as to be in contact with the outer periphery of the casting drum 1.

During operation of the apparatus for manufacturing a rapidly solidified thin plate configured as described above, the molten steel 3 in the tundish 8 is supplied from the nozzle 4 into the side dams 2 and 2 and is driven to rotate. The solidification cell 9 is formed by being cooled by contact with the surface of the solid-state cell 1. Further, after passing through the casting drums 1, 1, the solidification cell 9 is cast into a thin cast piece 5, pulled out by a pinch roll 7 at a predetermined speed via guide rolls 6, 6a, and sent to the next step. .

At the time of the casting, a large number of fine recesses 13 are formed in the surface 1a of the casting drums 1, 1 which are driven to rotate, and the metal powders 14 such as iron powder are supplied from the metal powder supply device 11 to the recesses. Is supplied continuously or intermittently in accordance with the pitch of the recess 13.

Then, as shown in FIG. 5, when the metal powder 14 filled in the recess 13 comes into contact with the molten steel 3, it is sintered and joined to the solidification cell 9 of the molten steel 3 (c is a sintered joint),
The sintered metal powder 14 generates a spike effect and finely restrains the solidification cell 9, thereby releasing the thermal strain accompanying the solidification shrinkage of the solidification cell 9 and reducing the thermal stress. Thereby, the solidification of the slab 5 is made uniform, and the occurrence of minute cracks on the surface of the slab 5 can be prevented.

[0018]

[Experimental Example] An experimental example using the apparatus for manufacturing a rapidly solidified thin plate according to the embodiment shown in FIG. 1 will be described below.

The casting drum 1 has a diameter of 600 mm and a width of 600 mm.
mm, the concave diameter D is 500 μm × depth H
Was formed so that the area ratio of the surface of the casting drum 1 was 30%, and iron powder was applied as the metal powder to be filled in the fine recesses 13. In the above apparatus, molten steel 3 was made of low carbon steel of c = 0.04%, casting speed was 40 m /
As a result of manufacturing the slab 5 under the casting conditions of 2 mm in slab thickness and 2 mm in thickness, it was confirmed that fine cracks did not occur on the surface of the slab 5.

[0020]

The present invention is configured as described above.
According to the present invention, a metal powder filled in a concave portion formed on the surface of a casting roll is sintered and bonded to a solidification cell to generate a spike effect, thereby releasing thermal strain accompanying solidification shrinkage of the solidification cell. Thus, thermal stress is reduced. As a result, the solidification cells of the slab are made uniform, and the occurrence of fine cracks on the surface of the slab can be prevented, thereby improving the quality of the slab.

[Brief description of the drawings]

FIG. 1 is a side view showing the structure of a rapidly solidified thin plate manufacturing apparatus according to an embodiment of the present invention.

FIG. 2 is an enlarged partial sectional view of an outer peripheral portion of a casting drum in the embodiment.

FIG. 3 is a view showing a modified example of the concave portion of the outer peripheral portion of the casting drum.
Appropriate figure.

FIG. 4 is a view as viewed in the direction of the arrow Z in FIG. 2;

FIG. 5 is an operation explanatory view in the embodiment.

FIG. 6 is a side view of a conventional rapid solidification thin plate manufacturing apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Casting drum 2 Side dam 3 Molten steel 4 Nozzle 5 Cast piece 8 Tundish 9 Solidification cell 11 Metal powder supply device 12 Rotary brush 13 Concave part 14 Metal powder c Sintered joint

Claims (2)

[Claims] 1. A solidified shell is formed by supplying molten metal between a pair of cooling-type casting drums rotating in opposite directions to each other, and bringing the molten metal into contact with the surface of the casting drum and cooling the molten metal. In casting thin slabs,
Forming a large number of fine recesses on the surface of the casting drum, filling the recesses with metal powder, bringing the metal powder into contact with the molten metal by rotating the casting drum, and sintering the solidified shell of the molten metal. A method for producing a rapidly solidified thin plate, characterized by binding. 2. A rapidly solidified sheet manufacturing apparatus for forming a solidified shell by bringing molten metal into contact between a pair of cooling casting drums rotating in opposite directions to form a solidified shell and casting a slab of a metal sheet. The casting drum has a number of fine recesses formed in the surface thereof, and a metal powder supply means for supplying a metal powder for sintering to the recess, and a sintered metal powder remaining in the recess. A rapidly solidified thin plate manufacturing apparatus, comprising: