JPH04224059A - Tundish with induction heating - Google Patents

Abstract

PURPOSE:To present the tundish with induction heating which reduces the remainder of the molten steel on the continuous manufacture of the steel and to prevent the interruption of the circuit of secondary electric current caused on the pinch effect. CONSTITUTION:On the tundish which is divided with a partition block into a molten metal receiving part and a molten metal supplying part to pour the molten metal to the mold, the space is provided passing through vertically the partition block and an iron core wound with the induction heating coil is inserted in the above space, and the molten metal receiving part and the supplying part are communicated with two pieces of the hollow refractory buried in the pertition block. The bottom of the hollow refractor is set lower than the bottom of the molten metal receiving part and a groove whose sectional area is larger than the sectional area of the above hollow refractory is set at the front of the hollow refractory so as to communicate with the two pieces of the hollow refractory, further the bottom of the molten metal supplying part is set lower than the bottom surface of the hollow refractory.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention is a continuous casting method that reduces the amount of molten steel remaining in the tundish in continuous casting of steel, and prevents the interruption of the secondary current path due to the pinch effect to achieve stable induction heating. The present invention relates to an induction heating tundish for use.

0002

BACKGROUND OF THE INVENTION The degree of heating of the molten metal in a continuous casting tundish (hereinafter referred to as SH) has a great effect on the quality of slabs and the stability of operation.

[0003] Therefore, it is desirable for quality and operational reasons to always control the SH within the target range, but in general, due to the influence of heat dissipation from the molten metal into the atmosphere or into the refractory, the SH decreases, especially at the beginning and end of casting. could not adequately compensate for the decline in

[0004] Therefore, in recent years, attempts have been made to provide a heating function to the continuous casting tundish to prevent a decrease in SH at the initial and final stages of casting. Specifically, induction heating and plasma heating are often used.

[0005] Previously reported examples of induction heating type tundishes include the one published in Japanese Patent Publication No. 63-39343, in which a stepless hollow refractory in contact with the bottom of the tundish was used to connect both spaces partitioned by refractories. Things can be mentioned.

This method has the problem that molten metal and slag remain in the receiving chamber at the end of casting, making it difficult to repair the tundish and reducing the yield of molten metal.

[0007] Japanese Patent Publication No. 63-39343 describes a stepless opening in contact with the bottom surface of the receiving chamber, but with this method, molten steel and slag do not flow into the receiving chamber or into the receiving chamber after casting is completed. There is a problem remaining in the opening.

[0008] Japanese Patent Publication No. 2-37813 discloses that a shielding block is formed between a hot water receiving chamber and a hot water supply chamber in a tundish,
This shielding block has two holes communicating with the hot water receiving chamber and the pouring chamber, and a tundish induction heating device is described in which a core having an induction heating coil is removably communicated with the vertically communicating hole. ing.

[0009] Japanese Patent Publication No. 2-8821 discloses that a shielding block is formed between the hot water receiving chamber and the hot water supply chamber in the tundish, and this shielding block is connected to the hot water receiving chamber and the hot water pouring chamber, and is connected to the hot water receiving chamber and the hot water pouring chamber. Although it is mentioned that two holes or grooves are made which are inclined so that the chamber is elevated, this method concerns the flotation separation of inclusions.

0010

[Problems to be Solved by the Invention] As shown in FIG. 5, an induction heating device for continuous casting has a tundish with a shielding block 1, a molten metal receiving part 2 for receiving molten steel from a ladle, and a hot water supply for injecting molten steel into a mold. 3, and the shielding block is provided with a space 4 penetrating in the vertical direction,
A device is used in which a hot water receiving part and a hot water supply part are communicated through a plurality of hollow refractories 5 buried in a shielding block through an iron core 4-1 wrapped with an induction heating coil.

[0011] In casting using this induction heating device, the molten steel generally injected from the ladle is heated by a secondary current within the hollow refractory during the process of moving from the steel receiving section to the hot water supply section.

[0012] When pouring from the ladle is completed, the molten steel in the tundish and the slag and heat insulating material on the surface of the molten steel descend as casting continues, and at the end of casting, part of the molten steel and most of the slag and heat insulating material are removed.ヾThe entire amount remains in the tundish.

In particular, when molten steel in contact with slag is left partially in the tundish in order to reduce defects caused by inclusions in the slab, approximately several tons to 10 tons of molten steel and slag remain.

[0014] At this time, if the steel receiving part and the hollow refractory are in contact with each other without a step difference, the remaining molten steel and slag solidify and block the hollow refractory, which poses a serious problem when reusing the hollow refractory. The same applies to the case where the hot water supply part and the hollow refractory are in contact with each other without any step.

[0015]

[Means for Solving the Problems] The present invention is directed to solving the above problems. FIG. 1 is a vertical sectional view of the main part of the present invention, and FIG. 2 is a plan sectional view. As shown in the figure, the tundish is divided by a shielding block 1 into a receiving part 2 for receiving molten steel from a ladle and a hot water supplying part 3 for injecting molten steel into the mold, and the shielding block has a space 4 penetrating it in the vertical direction. An iron core (not shown) wrapped with an induction heating coil is passed through the

In the induction heating tundish in which the hot water receiving part and the hot water supply part are connected by two hollow refractories 5 buried in a shielding block, when the hot water receiving part 2 and the hollow refractories 5 are connected, the hollow refractories are The bottom surface 6 is made lower than the bottom surface 7 of the receiving part, and a groove 8 with a depth h and a width d is formed in the front part of the hollow refractory [1].
The two refractories are connected to each other so as to satisfy the formula, and when connecting the hot water supply section 3 and the hollow refractory 5,
A part of the molten steel discharged from the receiving part 2 through the hollow refractory 5 and slag can be retained therein.

By making the bottom surface 9 of the hot water supply section lower than the bottom surface of the hollow refractory, it is possible to prevent molten steel and slag from remaining in the hot water receiving section and the hollow refractory after casting is completed. Groove 8
Cross-sectional area (h x d) ≧ Cross-sectional area of hollow refractory ... [
1] However, h≧50mm, d≧50mm. Here, the cross-sectional area of the hollow refractory refers to the cross-sectional area viewed as a passage for molten steel.

First, the reason why the bottom surface 6 of the hollow refractory is made lower than the bottom surface 7 of the hollow refractory and the groove 8 is provided in the front part of the hollow refractory 5 when connecting the receptacle 2 and the hollow refractory 5 is as follows. This will be explained below.

The superheat of the molten steel in the tundish after completion of pouring into the ladle generally decreases as the amount of remaining molten steel decreases.

In addition, even if induction heating is attempted, since the height of the molten steel is low, the pinch effect blocks the secondary current path in the hollow refractory 5, making heating impossible. superheat decreases and fluidity deteriorates. Therefore, in the present invention, the bottom surface of the hollow refractory is made lower than the bottom surface of the molten metal receiving part.

[0021] Furthermore, a groove with a depth h and a width d is provided in the front part of the hollow refractory from the bottom surface of the steel receiving part to the bottom surface of the hollow refractory,
The cross-sectional area (h×d) of this groove is made equal to the internal cross-sectional area of the hollow refractory.

The reason for this is that the two hollow refractories and the groove form a path for the secondary current generated by induction heating, ensuring high heating efficiency and reducing the amount of remaining molten steel when the pinch effect occurs. It's for a reason.

Furthermore, the depth h and width d of the groove are shown in FIG.
Based on the experimental results regarding the blockage of the hollow refractory inlet with bare metal shown in , both h and d should be 50 mm or more.

Next, in the present invention, when connecting the hot water supply part and the hollow refractory, the bottom surface of the hot water supply part is fixed so that a part of the molten steel discharged from the hot water receiving part through the hollow refractory and slag can stay there. By making the height lower than the bottom surface of the hollow refractory, molten steel and slag are prevented from remaining in the receiving part and inside the hollow refractory after casting is completed.

[0025]

According to the present invention, the presence of the groove prevents the secondary current from being cut off due to the pinch effect during induction heating. In addition, the performance of discharging molten steel and slag to the hot water receiving part and the hot water supply part in the hollow refractory is greatly improved, allowing smooth casting work.

[0026]

[Example] Al-killed steel for bar steel was cast using a 4-strand bloom continuous caster. T-type TD with a capacity of 35 tons
An induction heating device with a capacity of 1000 kW was installed on each of the 1st and 2nd strand sides, and the 3rd and 4th strand sides.

[0027] Five charges were cast for each of the tundish constructed according to the present invention and the conventionally constructed tundish (method in which there is no step between the bottom of the hot water receiving chamber and hot water supply chamber and the bottom of the hollow refractory). The amount of molten metal remaining in the tundish was measured using a load cell at the bottom of the tundish and compared.

The inner diameter of the hollow refractory is 100 mm, and the groove sizes are d=90 mm and h=87 mm. The applied power is 250 KWhr to each heating device.

FIG. 4 shows a comparison of the amounts of molten steel remaining in the tundish when the tundish of the present invention is used and when a conventional tundish is used.

It can be seen that according to the present invention, the amount of remaining hot water in the tundish has been significantly reduced from the conventional average of 2.6 tons to an average of 0.6 tons. Furthermore, even when the amount of molten steel decreased considerably, no interruption of the secondary current due to the pinch effect occurred.

[0031]

According to the present invention, it is no longer necessary to remove the solidified ingot inside the tundish after casting or to replace the hollow refractories frequently, which is extremely effective in improving productivity and reducing the cost of refractories.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of a main part showing an induction heating tundish according to the present invention.

FIG. 2 is a cross-sectional plan view of the tundish shown in FIG. 1;

FIG. 3 is a diagram showing the relationship between the metal blockage at the entrance of the hollow refractory and the dimensions of the groove.

FIG. 4 is an explanatory diagram showing the effects of the present invention.

FIG. 5 is a perspective view showing the configuration of a conventional tundish.

[Explanation of symbols]

1 Shielding block 2　Hot water receiving part 3　Hot water supply section 4 Space 5 Hollow refractories 6 Hollow refractory bottom 7　Bottom surface of the hot water receiving part 8 groove 9 Bottom of hot water supply part

Claims (1)

[Claims] Claim 1: A tundish is partitioned by a shielding block into a receiving part for receiving molten steel from a ladle and a supplying part for injecting molten steel into the mold, and the shielding block is provided with a vertically penetrating space in which an induction heating coil is wound. In a tundish, the hot water receiving part and the hot water supply part are connected through two hollow refractories embedded in a shielding block through the iron core, and the bottom of the hollow refractory is installed lower than the bottom of the hot water receiving part. A groove with a depth h and a width d is provided in the front part of the hollow refractory on the hot water part side so as to satisfy the following formula [1] and communicate with the two hollow refractories, and the bottom of the hot water supply part is An induction heating tundish characterized by being installed at a position lower than the bottom surface of the hollow refractory. Cross-sectional area of groove ≧ Cross-sectional area of hollow refractory ... [
1] However, h≧50mm d≧50mm