JPH06106310A - Nozzle for casting - Google Patents

Abstract

PURPOSE:To reduce the developing rate of pin holes in a cast slab by providing at least one or mare of pressure measuring holes penetrating plural fine holes from the inner wall to the outer wall of a nozzle for casting in the measuring holes. CONSTITUTION:In packing material providing a base material 11 in an immersion nozzle and SUS-made socket metal tool 12 for connecting guiding pressure piping, the pressure measuring hole is arranged. As this material, coating material or heat resistant-mortar is used. A metal hoop 14 fixes the socket metal tool 12. Plural pieces of organic fibers 15 are arranged from the inner wall to the outer wall of the nozzle and eliminated at the time of preheating the immersion nozzle to become the fine pressure measuring holes. The material of a hot sealing material 16 is constituted of Al2O3, SiO2 and water glass. Therefore, by constituting the measuring hole with plural fine holes, the inner pressure in the nozzle can be measured in good precision and the always stable condition, and gas quantity mixed in the mold can be made to be the suitable quantity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a casting nozzle for detecting a process amount for grasping a casting condition in continuous casting of steel.

[0002]

2. Description of the Related Art A casting nozzle is used between a ladle and a tundish, and between a tundish and a mold, and one of the functions required to supply molten steel in a stable state to the mold. Is.

Conventionally, as an attempt to measure and control the gas pressure in the casting nozzle, for example, a copper pipe is connected to a nozzle having a slit, and the internal gas is sucked by a pump in an amount corresponding to the flow rate of the upper nozzle Ar. A method of controlling pressure has been proposed.

[0004]

Conventionally, an inert gas is blown into the casting nozzle from the outside to prevent the oxidation of molten steel, and the back pressure and flow rate thereof are controlled according to the casting speed and the TD head. . However, outside air leaks occurred during casting between the sliding nozzle surfaces for adjusting the pouring amount and the joint part of the intermediate nozzle directly below the sliding nozzle, and the amount of gas mixed into the mold was adjusted to an appropriate value. Absent. Therefore, there is a problem of quality deterioration such as pinhole generation due to excessive mixed gas and powder entrainment due to boiling water.

An object of the present invention is to provide a nozzle having a measuring hole having a shape capable of accurately measuring the internal pressure of the casting nozzle online for a long time, which cannot be grasped by the conventional back pressure detection of the blown gas. To do.

[0006]

The gist of the present invention is to provide at least one or more pressure measuring holes on the inner wall of the nozzle, and to provide a plurality of pressure measuring holes from the inner wall to the outer wall of the casting nozzle. A casting nozzle characterized by being formed from fine holes.

The present invention will be described below with reference to the drawings.
FIG. 1 shows a case where the present invention is applied between a tundish upper nozzle and a dipping nozzle. In the figure,
Reference numeral 1 is an upper nozzle attached to the bottom of the tundish, 2a, 2b, 2c are sliding plates for controlling the flow rate of the molten metal, 3 is an intermediate nozzle, and 4 is an immersion nozzle having an internal pressure measuring hole. The immersion nozzle 4 is provided with a pressure measuring hole 5 penetrating the inner wall of the nozzle. Further, a pressure guiding pipe 6 is connected to the pressure gauge 7 in the pressure measuring hole 5 to measure the gas pressure in the immersion nozzle. It is like this. Further, the in-nozzle pressure signal detected by the pressure gauge 7 and converted into an electric signal is input to the controller 8 to adjust the set value of the flow rate of the inert gas blown from the upper nozzle to an optimum value. In addition, 9 is a molten metal and 10 is a mold.

FIG. 2 is a view showing a detailed structure of the nozzle internal pressure measuring hole. Reference numeral 11 is a base material of the immersion nozzle, 12 is a SUS socket metal fitting for connecting a pressure guiding pipe, and 13 is a filling material, and a pressure measuring hole is installed therein. The material is a coating material or heat resistant mortar. Reference numeral 14 is a metal hoop for fixing the socket fitting 12, and reference numeral 15 is a plurality of organic fibers having a diameter of 1 mm or less and provided from the inner wall to the outer wall of the nozzle. The organic fibers 15 disappear upon preheating of the immersion nozzle, and these become fine pressure measurement holes. Reference numeral 16 is a hot seal material made of Al ₂ O ₃ = 70 to 100%, SiO ₂ =
It is composed of 30 to 0% and water glass outer cover 30 to 80%.

[0009]

[Operations and Examples] The internal pressure of the nozzle is-
It has been confirmed by measurement with an actual machine that it shows a negative pressure of about 3000 mmAq. On the other hand, it has been confirmed that the nozzle internal pressure fluctuates in response to fluctuations in operating conditions. For example, when the TD head decreases, the internal pressure of the nozzle increases. This is TD
The opening of the sliding plate 2 is automatically controlled to gradually increase in order to keep the molten metal injection amount constant when the head decreases, but when the Ar flow rate blown from the upper nozzle is constant, the apparent molten metal is Since the specific gravity decreases, the ability of the molten metal to suck the gas inside the immersion nozzle 4 decreases,
The pressure inside the immersion nozzle increases. A similar phenomenon occurs when the casting speed is reduced.

On the other hand, in the case where the measuring hole of the present invention is composed of a plurality of fine holes, if there is only one measuring hole, it becomes impossible to measure if it is clogged. Therefore, it becomes possible to measure the nozzle internal pressure with high accuracy in a stable state. As a result, the amount of gas mixed in the mold can be set to an appropriate amount, and the above-mentioned inconvenience does not occur.

[0011]

FIG. 3 is a comparison of the slab pinhole occurrence rate when the nozzle internal pressure control is performed using the nozzle of the present invention as compared with the case where the conventional nozzle is used. The slab pinhole, which was generated due to the change in the gas distribution in the molten metal passing through the nozzle due to the increase in the nozzle internal pressure, was 0.45 (pieces / m ² ) in the past when the nozzle internal pressure was controlled to a constant value. The rate of one-sided pinholes decreased to 0.1 (pieces / m ² ).

[Brief description of drawings]

FIG. 1 is a sectional view showing an example in which the nozzle of the present invention is applied between a tundish upper nozzle and a dipping nozzle.

FIG. 2 is a detailed cross-sectional view of a nozzle internal pressure measurement hole.

FIG. 3 is a graph showing a slab pinhole occurrence rate in the case where the nozzle of the present invention is applied, in comparison with the conventional means.

[Explanation of symbols]

1 Tundish Upper Nozzle 2 Sliding Plate 3 Intermediate Nozzle 4 Immersion Nozzle 5 Pressure Measuring Hole 6 Pressure Piping 7 Pressure Gauge 8 Controller 9 Molten Metal 10 Mold 11 Immersion Nozzle Base Material 12 Socket Metal Fitting 13 Filling Material 14 Metal Hoop 15 Organic Fiber 16 Hot seal material

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Hiroaki Mizuta, Inventor Hiroaki Mizuta, 1 Kimitsu, Kimitsu, Chiba Pref. Within the Nippon Steel Corporation (72) Inventor Masuyuki Miwa 1-1, Higashihama-cho, Hachimansai-ku, Kitakyushu, Fukuoka Saki Ceramics Co., Ltd.

Claims (1)

[Claims] 1. A casting nozzle characterized in that at least one pressure measuring hole is provided on the inner wall of the nozzle, and the measuring hole is formed by a plurality of fine holes penetrating from the inner wall of the nozzle to the outer wall.