JPH06102254B2 - Continuous casting method for metal ribbon - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention provides a metal thin film produced when a molten metal is supplied between the surfaces of a pair of rotating cooling drums to continuously produce a thin metal strip. The present invention relates to a continuous casting method in which a strip is smoothly taken out from a drum gap portion.

[Conventional technology]

Recently, attention has been focused on a method for directly producing a thin strip having a thickness of about several mm close to the final shape from a molten metal such as molten steel. With this continuous casting method, there is no need for a hot rolling step, and the rolling to the final shape may be mild, so the steps and equipment can be simplified.

As one of such continuous casting methods, there is a twin drum method (see Japanese Patent Laid-Open No. 60-137562). In this system, as shown in FIG. 3, a pair of cooling drums 1a and 1b that rotate in opposite directions are horizontally arranged and partitioned by the pair of cooling drums 1a and 1b and side dams 2a and 2b. The basin 3 is formed in the recess. The molten metal supplied to the basin 3 is cooled and solidified at the portions in contact with the cooling drums 1a and 1b to become solidified shells.

The solidified shell moves to a so-called drum gap portion where the pair of cooling drums 1a and 1b face each other at a position closest to each other as the cooling drums 1a and 1b rotate. In the drum gap portion, the solidified shells formed on the surfaces of the respective cooling drums are pressed and integrated with each other to form the desired metal ribbon 4.

[Problems to be Solved by the Invention]

In this type of continuous casting apparatus, it is difficult to exactly match the growth conditions of the solidified shell around the cooling drums 1a and 1b. Therefore, the solidified shells grown on the peripheral surfaces of the respective cooling drums 1a and 1b differ from each other in the timing at which the solidified shells are separated from the peripheral surface. Further, it is difficult to accurately synchronize the rotation speeds of the cooling drums 1a and 1b, and the deviation of the rotation speeds also causes vibrations, shakes and the like. Furthermore, at high speed, the cooling drums 1a, 1
Since the metal thin strip 4 is sent out from the drum gap portion of b, the metal thin strip 4 to be carried out meanders greatly due to vibration, shake, or the like in some cases. These vibrations, shakes, and the like promote the formation of lateral cracks in the metal ribbon 4, and also, in the relationship with the metal ribbon transfer device (not shown) arranged on the downstream side of the continuous casting device, cooling is performed. It becomes difficult to adjust the speed between the drums 1a and 1b and the transfer device.

As a means for solving such a problem, it is conceivable to press the metal ribbon carried out from the drum gap portion against one cooling drum. In FIG. 4, for this purpose, the pressing roll 6 is opposed to one cooling drum 1b, and the metal ribbon 4 coming out from the drum gap portion 5 is conveyed along the peripheral surface of the cooling drum 1b. The pressing roll 6 prevents the meandering and improves the running state of the metal ribbon 4.

However, even in this case, it is not possible to completely prevent the formation of the void portion 7 between the metal ribbon 4 immediately after coming out of the drum gap portion 5 and the peripheral surface of the cooling drum 1b.
The gap 7 requires a large force when the metal strip 4 is peeled from the other cooling drum 1a, and the compressive force acts on the metal strip 4 between the drum gap 5 and the pressing roll 6. It is caused by doing.

In the void portion 7, the metal ribbon 4 is not in contact with the cooling drum 1b, so that the metal ribbon 4 is cooled slowly. Then, the void 7 is formed by the temperature of the molten metal supplied to the pool 3
Amount, cooling capacity of cooling drums 1a, 1b, rotation speed, presser roll 6
Changes irregularly due to various factors such as the number of revolutions of the. Therefore, the cooling conditions for cooling the metal ribbon 4 coming out of the drum gap portion 5 with the cooling drum 1b are not stable, and the quality of the obtained metal ribbon 4 is not uniform.

In view of this, the present invention maintains a good contact state of the metal ribbon with the cooling drum by eliminating the gap portion formed between the metal ribbon immediately after coming out of the drum gap portion and the cooling drum, and the metal foil is maintained. While stabilizing the running of the belt,
The object is to produce a metal ribbon with stable quality under uniform cooling conditions.

[Means for Solving the Problems]

The continuous casting method of the present invention, in order to achieve the object, when supplying molten metal between the surfaces of a pair of rotating cooling drums to produce a metal ribbon, the metal immediately after being sent out from the drum gap portion. A high-speed fluid is blown onto the ribbon, and the metal ribbon is pressed against one of the cooling drums.

〔Example〕

Hereinafter, the features of the present invention will be specifically described by way of examples with reference to the drawings.

FIG. 1 is a sectional view showing the outline of a continuous casting apparatus used in the examples of the present invention. Incidentally, in FIG. 1, parts corresponding to the members shown in FIGS. 3 and 4 are designated by the same reference numerals. Also, in FIG. 1, the side weir is not shown.

In this embodiment, a nozzle 8 for spraying a high-speed fluid such as air or an inert gas is arranged on the metal ribbon 4 immediately after being discharged from the drum gap portion 5 of the cooling drums 1a and 1b. . Water, nonflammable oil, etc. can also be used as the high-speed fluid. By spraying the high-speed fluid, the thin metal strip 4 is pressed against the cooling drum 1b so as to come into close contact therewith, and the generation of the void portion 7 shown in FIG. 4 is prevented.

The speed at which the high-speed fluid ejected from the nozzle 8 hits the slab is as follows:
Is completely peeled off, and is set to a value required to press the metal ribbon 4 against the peripheral surface of the cooling drum 1b with a predetermined pressure. For this reason,
The velocity of the high-speed fluid is preferably 1/2 or more of the speed of sound. If the velocity of the high-speed fluid is less than 1/2 of the sonic velocity, the force with which the metal ribbon 4 is pressed against the cooling drum 1b becomes small, and the effect of preventing the formation of the void 7 is insufficient.

The thin metal strip 4 sent out from the drum gap portion 5 is conveyed to the press roll 6 while being in close contact with the peripheral surface of the cooling drum 1b in this manner. Therefore, the cooling effect that the metal ribbon 4 receives between the drum gap portion 5 and the pressing roll 6 is constant, and the properties of the obtained product are uniform. Further, since the thin metal strip 4 immediately after exiting the drum gap portion 5 is bent with a constant curvature along the peripheral surface of the cooling drum 1b, the occurrence of horizontal wrinkles or the like due to the void portion 7 is not seen.

The range where the high-speed fluid is sprayed is the drum gap portion 5
It is also possible to make it just below. However, the high-speed fluid may be sprayed onto the metal ribbon 4 over the range from immediately below the drum gap portion 5 to the presser roll 6. Thus, when the high-speed fluid is sprayed over a wide range, the free movement of the metal ribbon 4 is restricted, and the above-mentioned vibration, shake, meandering, etc. can be completely prevented. Further, when the pressure of the high-speed fluid is made sufficiently large and the weight of the metal ribbon 4 is supported by this injection pressure, the pressing roll 6 can be omitted.

The metal ribbon 4 that has passed through the pressing roll 6 is guided to the transport roll 9 and is transported to the next step.

The high-pressure fluid sprayed on the metal ribbon 4 leaves the slab while cleaning the slab (and the drum surface immediately below the drum gap). Further, when an inert gas is used, it is possible to suppress the surface oxidation of the slab.

FIG. 2 is a graph specifically showing the effect of spraying a high-speed fluid.

In this example, molten steel having a stainless steel composition and a temperature of 1490 ° C. is supplied to the pool 3 and a metal strip 4 having a thickness of 1.7 mm is used.
Was produced at a casting speed of 95 m / min. Then, the inert gas is discharged from the nozzle 8 toward the drum gap portion 5 at a sound speed of 0.9.
Sprayed in double. As a result, the metal ribbon 4 becomes the cooling drum.
Since it was conveyed in close contact with the peripheral surface of 1b, the cooling conditions were uniform and variations in the structure of the obtained product were suppressed. With the homogenization of this structure, the mechanical, chemical and thermal properties of the product were also uniform. On the other hand, in the case where the inert gas was not injected from the nozzle 8, the variation in crystal grain size and the average value were large, as shown as a comparative example in FIG.

〔The invention's effect〕

As described above, in the present invention, the metal ribbon that is carried out from the drum gap portion by blowing a high-pressure fluid to the metal ribbon immediately after leaving the drum gap portion and pressing it against one cooling drum. And the contact state with the surroundings of the cooling drum are improved. Therefore, the metallic ribbon is cooled uniformly by the cooling drum under stable conditions. Further, the spraying of the high-pressure fluid also has the function of preventing vibration, blurring, meandering, etc. of the metal ribbon. In this way, according to the present invention, a metal ribbon of excellent quality is manufactured, and the metal ribbon is stably carried out from the drum gap portion.

[Brief description of drawings]

FIG. 1 shows the outline of the continuous casting apparatus used in the examples of the present invention, and FIG. 2 is a graph showing the effect of the present invention concretely. On the other hand, FIG. 3 shows a conventional continuous casting apparatus for metallic ribbons, and FIG. 4 is a diagram for explaining problems in the apparatus. 1a, 1b: Cooling drum, 2a, 2b: Side weir 3: Hot water pool part 4: Metal ribbon, 5: Drum gap part 6: Holding roll, 7: Void part 8: Nozzle, 9: Conveying roll

(72) Inventor, Kunimasa Sasaki 4-6-22 Kannon Shinmachi, Nishi-ku, Hiroshima City, Hiroshima Prefecture Mitsubishi Heavy Industries, Ltd. Hiroshima Works (72) Inventor Keiichi Yamamoto 4-6-22, Kannon Shinmachi, Nishi-ku, Hiroshima City, Hiroshima Prefecture Issue Mitsubishi Heavy Industries, Ltd. Hiroshima Research Laboratory (56) Reference JP-A-61-229445 (JP, A)

Claims (1)

[Claims] 1. When a molten metal is supplied between the surfaces of a pair of rotating cooling drums to produce a metal ribbon, a high-speed fluid is sprayed onto the metal ribbon immediately after being sent out from the drum gap portion, A continuous casting method for a metal ribbon, comprising pressing the metal ribbon against one of the cooling drums.