JP4099257B2 - Lower nozzle for discharging molten metal - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a lower nozzle for discharging a molten metal, and more particularly to a lower nozzle for discharging a molten metal, which prevents cracking of the nozzle and improves durability.
[0002]
[Prior art]
The lower nozzle for discharging molten metal is attached to the lower end of a molten metal discharging device, for example, a slide gate device for adjusting the amount of molten metal discharged in the ladle, and controls the flow of molten metal discharged from the slide gate device. It is a device to do.
[0003]
In recent years, a lower nozzle 31 for molten metal discharge, for example, a lower nozzle 31 for continuous casting as a lower nozzle for continuous casting of steel is a refractory nozzle body 33 having a molten steel flow path 32 at the center as shown in FIG. Further, the one having an iron skin 34 surrounding the nozzle body 33 is used.
[0004]
In order to attach the nozzle 31 to, for example, a slide gate device, the iron skin 34 and the nozzle body 33 are provided with attachment step portions 35 and 36, respectively.
[0005]
The mounting step 35 provided on the iron skin 34 is provided on the outlet 37 side (lower side) of the nozzle 31 with respect to the step 36 provided on the nozzle body 33.
[0006]
[Problems to be solved by the invention]
When the nozzle 31 having such a structure is attached to the lower end portion of the slide gate device by the attachment tool, the attachment step portion 35 provided on the iron skin 34 is always pressed toward the slide gate device by the attachment tool and attached to the slide gate device. . Accordingly, a pressing force F0 always acts on the mounting step portion 35 of the iron skin 34 and in the vicinity of the mounting step portion 35, and the step portion 36 provided on the nozzle body 34 facing the mounting step portion 35 is also caused by the pressing force. Stress acts. When the stress due to the pressing force acts on the stepped portion 36, the stepped portion 36 that is weak in thermal stress in shape has a crack C from the stepped portion 36 due to the synergistic effect of the thermal stress due to the molten steel and the stress due to the pressing force, and the molten steel leaks. It was dangerous.
[0007]
The present invention has been made in consideration of the above-described circumstances, and an object of the present invention is to provide a lower nozzle for discharging molten metal that is safe and highly durable.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, the invention of claim 1 of the present invention is a refractory product having a molten metal inlet and outlet at both ends and a molten metal discharge channel penetrating from the inlet to the outlet. In the lower nozzle for molten metal discharge comprising the nozzle body and the heat resistant cover surrounding the nozzle body, a mounting stage for mounting the lower nozzle for discharging the molten metal on the outer periphery of the heat resistant cover to the molten metal discharging device An annular neck portion in which the outer peripheral diameter of the nozzle body starts to increase and increase at least from the mounting step portion to the nozzle inlet side than the mounting step portion. It is a gist that it is a lower nozzle for discharging molten metal, characterized in that is formed in the nozzle body.
[0009]
In the invention of claim 2 of the present application, the annular neck portion of the nozzle body changes due to the difference in inclination between the outer periphery of the nozzle body on the outlet side from the annular neck portion and the outer periphery of the nozzle body on the inlet side from the annular neck portion. The gist of the present invention is the lower nozzle for discharging molten metal according to claim 1, wherein the lower nozzle is formed by a curved point.
[0010]
The invention of claim 3 of the present application is characterized in that the heat-resistant cover is an iron skin and the mounting step portion is formed to have an annular surface perpendicular to the axial direction of the nozzle body. It is the gist that it is the lower nozzle for molten metal discharge described in 1.
[0011]
The invention of claim 4 of the present application is characterized in that a taper portion having the same taper as the outer periphery of the nozzle body at the corresponding portion is connected to the outlet side of the mounting step portion. The gist of the invention is the lower nozzle for discharging molten metal as described above.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments and implementation status of a molten metal discharge nozzle according to the present invention will be described below with reference to the accompanying drawings.
[0013]
A lower nozzle 1 for discharging a molten metal according to the present invention as shown in FIG. 1 is composed of a refractory nozzle body 2 and a heat-resistant cover surrounding the nozzle body 2, for example, an iron skin 3.
[0014]
The nozzle body 2 is provided with a molten metal discharge channel 4 extending in the axial direction in the center, and an inlet 5 and an outlet 6 are provided in the molten metal discharge channel 4. Further, the nozzle body 2 has a cylindrical shape, and the outer peripheral shape of the nozzle body 2 has a straight barrel portion 7 and an end portion of the straight barrel portion 7 as a starting point 8, and has a tapered portion 9 that tapers from the starting point 8. The taper portion 9 has a main body 11 having a different slope from the end point, that is, the inflection point 10a, and has a tapered shape.
[0015]
The gradient of the main body 11 is formed smaller than the gradient of the tapered portion 9, and a concave annular neck 10 is formed at the inflection point 10a. Here, the main body main portion 11 has a gradient of 0, that is, the main body main portion 11 extending from the neck portion 10 may have a cylindrical shape along the vertical line and having the same outer diameter.
[0016]
On the other hand, the iron skin 3 has a straight body portion 12 having an inner wall surface parallel to the straight body portion 7 of the nozzle body 2, and an entrance 5 from a neck portion 10 of the nozzle body 2 is provided at the end of the straight body portion 12. An annular mounting step portion 13 is provided on the side, and an iron skin main portion 14 extending from the mounting step portion 13 and having a gradient is formed. The iron skin main part 14 may also have a cylindrical shape without a gradient.
[0017]
The tapered portion 9 of the nozzle body 2 is formed so as to face the mounting step portion 13 described above, and the inflection point 10, so that the starting point 8 is located on the inlet 5 side (upper side) from the mounting step portion 13, That is, the neck portion 10 is formed so as to be positioned with a separation distance L on the outlet 6 side (lower side) from the mounting step portion 13. The gap formed between the nozzle body 2 and the iron skin 3 is filled with mortar 15.
[0018]
Since the lower nozzle 1 for discharging molten metal according to the present invention has the above-described structure, it is necessary to install the molten metal discharging device, for example, the slide gate device 20 in the slide gate device 20 as shown in FIG. The mounting step portion 13 of the iron skin 3 is pressed in the direction of the slide gate device 20 by the mounting tool 22 of the mounting device 21 provided to be rotatable. At this time, the fixture 22 is constantly pressed in the direction of the slide gate device 20 by the spring 23, and the mounting step 13 is always pressed by the fixture 22, so that the nozzle 1 is securely held by the slide gate device 20.
[0019]
The mounting step portion 13 is constantly pressed by the mounting tool 22, but the stress due to this pressing force does not directly act on the neck portion 10 of the nozzle body 2.
[0020]
Therefore, even if molten metal is flowed to the lower nozzle 1 for discharging the molten metal through the slide gate device 20 in such a state, only the thermal stress due to the molten metal acts on the neck portion 10 of the nozzle body 2, and the nozzle The main body 2 does not crack from the neck portion 10 that is weakest in terms of shape.
[0021]
In short, the lower nozzle 1 for discharging molten metal according to the present invention is provided with the neck portion 10 provided on the nozzle body 2 on the outlet 6 side (lower side) than the mounting step portion 13 provided on the iron shell 3. The neck portion 10 does not act synergistically with the stress caused by the pressing force and the thermal stress caused by the molten metal, and the neck portion 10 is not cracked, and has a long durability, and the lower nozzle 1 for discharging the molten metal. Is obtained.
[0022]
Next, another embodiment will be described.
[0023]
Further, an attachment step portion 27 facing the substantially middle portion of the taper portion 26 of the nozzle body 25 is positioned on the iron shell 24 as a heat resistant cover, and the neck portion 28 of the nozzle body 25 is further extended from the attachment step portion 27. A tapered portion 29 that is oriented in the direction and is substantially parallel to the tapered portion 26, for example, the tapered portion 26 is formed.
[0024]
By providing the taper portion 29 for stress dispersion on the iron skin 24, the stress applied to the nozzle body 25 via the iron skin 24 is dispersed by the fixture, and cracks other than the neck portion 28 of the nozzle body 25 are more effectively generated. To be prevented.
[0025]
The above is a description of specific examples of the present invention, and the scope of the present invention is not limited by the description of this embodiment.
[0026]
【The invention's effect】
According to the lower nozzle for discharging molten metal according to the present invention, it is possible to accurately prevent the occurrence of cracks from the neck portion of the nozzle body, and to provide a safe and durable lower nozzle for discharging molten metal.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of a lower nozzle for continuous casting according to the present invention.
FIG. 2 is a sectional view showing a state in which a continuous casting lower nozzle according to the present invention is incorporated in a slide gate device.
FIG. 3 is a cross-sectional view showing a main part of another embodiment of a continuous casting lower nozzle according to the present invention.
FIG. 4 is a sectional view showing a conventional lower nozzle for continuous casting.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Lower nozzle 2 for discharging molten metal Nozzle body 3 Heat-resistant cover 4 Flow path for discharging molten metal 5 Inlet 6 Outlet 7 Straight body 8 Starting point 9 Tapered part 10 Annular neck 10a Inflection point 11 Main part 12 Straight barrel portion 13 Mounting step portion 14 Iron skin main portion 15 Mortar 20 Slide gate device 21 Mounting device 22 Mounting device 23 Spring 24 Iron skin 25 Nozzle body 26 Tapered portion 27 Mounting step portion 28 Neck portion 29 Tapered portion

Claims (4)

Consists of a refractory nozzle body having a molten metal inflow port and an outflow port at both ends, a molten metal discharge channel penetrating from the inflow port to the outflow port, and a heat resistant cover surrounding the nozzle body In the molten metal discharge lower nozzle, a mounting step portion for mounting the molten metal discharge lower nozzle to the molten metal discharge device is provided on the outer periphery of the heat-resistant cover, and the outlet side of the nozzle from the mounting step portion In addition, a lower nozzle for discharging a molten metal is characterized in that an annular neck portion in which the outer diameter of the nozzle body starts to increase and change at least from the mounting step portion to the nozzle inlet side is formed in the nozzle body. . The annular neck portion of the nozzle body is formed by an inflection point due to a difference in inclination between the outer periphery of the nozzle body on the outlet side from the annular neck portion and the outer periphery of the nozzle body on the inlet side from the annular neck portion. The lower nozzle for discharging molten metal according to claim 1. The bottom for discharging molten metal according to claim 2, wherein the heat-resistant cover is an iron skin, and the mounting step portion is formed to have an annular surface in a direction perpendicular to the axial direction of the nozzle body. nozzle. The molten metal discharging device according to any one of claims 1 to 3, wherein a tapered portion having the same taper as the outer periphery of the nozzle body at a corresponding portion is connected to the outlet side of the mounting step portion. Lower nozzle.

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