JP2001009558A - Tundish injection pipe - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent an injection pipe body from breakage and detachment during using the pipe so as to use the injection pipe many times by forming a light-weight castable layer on the inner surface of the injection pipe composed of a refractory. SOLUTION: In this tundish injection pipe, a light-weight castable layer 2 is formed on an inner surface of an injection pipe body 1 composed of refractory. While the tundish injection pipe is being used, a base metal adhered at more than a specific thickness (weight) is peeled off together with a light-weight castable of required thickness. Also, during usage, the adhered base metal can be easily removed together with the light weight castable of required thickness. Furthermore, the inner face of the injection pipe body is formed into a taper in a way that the diameter is gradually expanded from the upper part to the lower part, so as to facilitate peeling-off of the adhered base metal during usage and removal of the adhered base metal after usage. In this case, it is preferable that an angle θ of the taper is 1-7 deg..

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tundish injection pipe used for continuous casting.

[0002]

2. Description of the Related Art In order to prevent secondary oxidation of molten metal injected from a ladle into a tundish, a tundish injection pipe is arranged so as to surround an injection flow of the molten metal, and an upper part is sealed and a lower part is sealed. It is used by being immersed in a molten metal contained in a tundish, and conventionally, a refractory made of a fixed refractory such as alumina-graphite or an amorphous refractory such as high alumina is known.

[0003]

However, in the conventional tundish injection pipe, when the molten metal injected into the tundish during use is adhered to the inner peripheral surface due to the splash of the metal, the weight of the injection pipe is increased due to the increase in weight. The cylindrical portion cannot withstand, and a load is locally applied to a portion above the portion where the metal is adhered, which may cause a crack to result in breakage and falling off. Also, in order to reduce costs, the demand for multiple use is increasing, but the inner diameter is narrowed due to the shape factor, that is, the adhesion of the base metal to the inner circumference rather than the material factor (melting). However, there is a problem that it is difficult to use it many times. In order to solve such a problem, there is known a tundish injection pipe provided with an inert gas supply passage and a perforated refractory capable of blowing out gas from an inner peripheral surface of the tundish injection pipe (Japanese Patent Application Laid-Open No. 5-293614). reference). According to the injection pipe of the tundish, gas is blown out from the inner peripheral surface to prevent the adhesion of the metal. However, even with the above-mentioned tundish injection pipe, the adhesion of the metal cannot be completely prevented, and when the gas blowing hole is clogged,
At present, the effect of preventing adhesion is further reduced, and as a result, the tundish injection pipe is damaged and dropped, and it is difficult to use the pipe many times. Accordingly, an object of the present invention is to provide a tundish infusion tube that can be used many times without causing damage to the infusion tube body during use.

[0004]

In order to solve the above-mentioned problems, a first tundish injection pipe according to the present invention is characterized in that a lightweight castable layer is formed on the inner periphery of an injection pipe body made of a refractory. Also, the second tundish injection tube is
The first aspect is characterized in that the inner periphery of the injection tube main body is formed in a taper whose diameter gradually increases from an upper part to a lower part. The angle of the taper is preferably 1 to 7 °. On the other hand, the thickness of the lightweight castable layer is
Preferably it is 5 to 30 mm. The specific gravity of the lightweight castable layer is preferably 1.2 or less. Further, the strength of the lightweight castable layer is preferably 1/3 or less of the strength of the injection pipe main body.

[0005] In the first tundish injection pipe, during use, the metal that has adhered to a certain thickness (weight) is peeled off with a light-weight castable having a required thickness. It can be easily done with a lightweight castable of the required thickness. Further, in the second tundish injection pipe, it becomes easier to remove the adhered metal during use and to remove the adhered metal after use.

As the refractory for forming the injection pipe main body, a fixed refractory such as alumina-graphite and an irregular refractory such as high (high) alumina and magnesia are used. On the other hand, the lightweight castable layer forming the lightweight castable layer is not particularly limited, but in consideration of the easiness of peeling of the adhered metal (excellent infiltration resistance), alumina-based fire-resistant aggregate and / or Mullite refractory aggregate 35-45 wt%, hydraulic transition alumina 40-6
0 wt%, foaming material 0.05 to 0.5 wt%, ceramic fiber 1 to 5 wt%, and microsilica 3 to 7 w
Those containing t% (see JP-A-07-0697743) are desirable.

When the taper of the inner circumference of the injection tube main body is less than 1 °, the same as in the case of the straight type, the adhered bullion is peeled off during use and further removal of the adhered bullion after use. Easiness is not recognized. On the other hand, if it exceeds 7 °, thermal stress or the like tends to concentrate on the flange portion, which causes cracks (falls). A more preferable taper angle is 2
５5 °.

If the thickness of the lightweight castable layer is less than 5 mm, the inner periphery of the injection pipe main body is exposed if the metal that has adhered to a certain thickness or more has peeled off during use. As in the case of the conventional product, the rate of occurrence of breakage and falling increases. In addition, it is not possible to easily remove the adhered metal after use, so that it cannot be used many times. On the other hand, 30mm
If it exceeds, there is no problem in use, but the cost is high because the lightweight castable is expensive. In addition, although it differs depending on the material of the injection pipe main body, the usage limit of the injection pipe main body due to erosion is exceeded, and the light-weight castable layer has an excessive thickness. More preferred thickness of the lightweight castable layer is 10 to 20 mm
It is.

When the specific gravity of the lightweight castable layer exceeds 1.2, there is a possibility that the injection pipe main body may be damaged and dropped before the adhered metal is peeled off due to its weight and the weight of the adhered metal. The lighter the weight, the more effective it is because no load is applied to the injection tube body.

The higher the strength ratio, the more effective it is because the base metal is more easily peeled off. On the other hand, if the strength ratio exceeds 1/3, the adhered metal does not peel off during use, and the injection pipe main body may be damaged and fall off.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to specific examples and comparative examples. Examples 1 to 9 and Comparative Examples 1 to 6 First, as shown in Tables 1 and 2, an alumina-graphite fixed refractory, a high alumina amorphous refractory,
As shown in FIG. 1, the upper inner diameter is 500 mm and the length is 800 m
m, a frustoconical cylindrical tube with a thickness of 30 mm (a taper angle θ is shown in Tables 1 and 2, but Comparative Example 3 is a cylindrical tube with a flange). As shown in Tables 1 and 2, light castable layers 2 having different thicknesses, bulk specific gravities, and strength ratios with respect to the injection pipe main body 1 are formed by a method such as pouring, troweling, or spraying to form various tundish injections. I got a tube. Next, when each tundish injection tube was subjected to an actual machine test, the adhesion state of metal, the possibility of multiple use, and the reason for disposal were as shown in Tables 1 and 2, respectively.

[0012]

[Table 1]

[0013]

[Table 2]

As described above, according to the first tundish injection pipe of the present invention, during use, the metal that has adhered to a certain thickness or more is peeled off with a lightweight castable of a required thickness. After use, the ingot metal can be easily removed together with the lightweight castable of the required thickness, so that the injection pipe body can be prevented from being damaged and dropped during use, and the injection pipe body can be used multiple times to be damaged by the material. You can do it to the limit. In addition, according to the second tundish injection pipe, it becomes easier to remove the adhered bullion during use and to remove the adhered bullion after use, so that the damage to the injection pipe body during use can be more effectively prevented. In addition, it is possible to reliably use the injection pipe main body a number of times up to the erosion limit due to its material.

[Brief description of the drawings]

FIG. 1 is a half sectional front view of a tundish injection tube according to the present invention.

[Explanation of symbols]

 1 Injection pipe body 2 Light weight castable layer θ Taper angle

Claims (6)

[Claims] 1. A tundish injection pipe characterized in that a lightweight castable layer is formed on the inner periphery of an injection pipe body made of a refractory. 2. The tundish injection pipe according to claim 1, wherein an inner circumference of said injection pipe main body is formed in a taper whose diameter gradually increases from an upper part to a lower part. 3. The tundish injection pipe according to claim 2, wherein the angle of the taper is 1 to 7 °. 4. The lightweight castable layer has a thickness of 5 to 5.
The tundish injection tube according to claim 1, 2 or 3, wherein the diameter is 30 mm. 5. The specific gravity of the lightweight castable layer is 1.
The number is 2 or less, wherein the number is 2 or less.
The described tundish injection tube. 6. The tundish injection pipe according to claim 1, wherein the strength of the lightweight castable layer is not more than one third of the strength of the injection pipe main body.