JPS5919558Y2 - porous plug - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a porous plug for blowing inert gas into molten steel transferred into a ladle for the purpose of removing harmful gases from the molten steel during refining.

Generally, when refining molten steel, in order to remove harmful gases from the molten steel, the molten steel before ingot formation is transferred to a ladle, and a porous plug attached to the bottom of the ladle is used to remove inert gas such as argon gas. Gas is injected into molten steel.

As shown in Fig. 2, this porous plug has a porous refractory 3 held around its lower part by a holding metal fitting 4 which is secured from an iron plate, and an inert gas inflow hole drilled in the bottom of the holding metal fitting 4 is connected to the porous refractory 3. A gas blowing pipe 5 is fixed, and as shown in Fig. 1, it is fixed to the bottom of a ladle with a refractory 2 attached to the inner periphery of an iron shell 1 using mortar joints or the like to prevent molten steel from leaking. It is used.

The refractory material 3 of the porous plug used in this way has the characteristic that molten steel cannot pass through it but gas can pass through it, but it has poor durability and needs to be replaced after two to several uses. It arises.

Therefore, when it is necessary to replace the porous plug, the method used is to tilt the ladle sideways, grasp the gas blowing tube 5 of the porous plug, and pull out the gas blowing tube 5 from the ladle using a hydraulic cylinder or the like. Since the upper refractory 3 is firmly fixed to the ladle with mortar joints or the like, it cannot be pulled out from the ladle with static force unless a considerably large tensile force is applied.

However, since the porous refractory 3 of the porous plug needs to be able to withstand the weight of the molten steel flowing into its upper part, it is strong against compressive force but weak against tensile force, so it is often used during drawing. The refractory 3 may break at the upper end of the holding hardware 4, that is, at the position indicated by line A-A in FIG. 2, which is the position where it is no longer held by the holding hardware 4.

Therefore, recently, a method has been adopted in which the ladle is turned sideways and the porous plug is punched out from the ladle by striking it from the inside of the ladle with a protruding rod 6, as shown in FIG.

In this punching, the protruding rod 6 cannot be made very thick because it needs to be able to be aligned with the porous plug, and furthermore, the ladle is in a high temperature state due to the residual heat of the molten steel, so it cannot be approached very closely. Bar 6
must be long, and although the protruding rod 6 is thin and long, it has a large amount of flexure, making it difficult to align its tip with the porous plug.
If the refractory 2 at the bottom of the ladle is accidentally hit, the refractory 2 will be destroyed, causing great damage that will significantly shorten the life of the ladle.

The present inventors thus succeeded in improving the shape of the porous plug so that the refractory 2 of the ladle would not be damaged when punching out the porous plug with the protruding rod 6 when replacing the porous plug. and completed the present invention.

That is, in the present invention, a concave portion for guiding the protruding rod is formed at the tip facing into the ladle, and the concave portion for guiding the protruding rod is formed horizontally or inclined toward the outer circumferential side from the outer surface protruding from the inner surface of the ladle to the bottom of the concave portion for guiding the protruding rod. The present invention provides a porous plug characterized in that a porous refractory in which a molten steel outflow groove is formed is held at its other end by a holding metal fitting to which a gas blowing pipe is fixed.

Hereinafter, one embodiment of the porous plug according to the present invention will be described in detail with reference to the drawings.

FIG. 4 is a perspective view of one embodiment of the porous plug according to the present invention, and FIG. 5 is an enlarged longitudinal sectional view showing the porous plug shown in FIG. 4 attached to a ladle.

In the drawing, reference numeral 3 denotes a porous refractory that constitutes the main body of the porous plug, and a protruding rod 6 is attached to the tip of the refractory 3, that is, the upper surface facing into the ladle when the porous plug is attached to the ladle. A protruding rod guide recess 3 a is formed to align the tip of the refractory with the axis of the refractory 3 .

Also, there is a horizontal line extending from the outer surface of the tip of this refractory 3, which protrudes from the inner surface of the refractory 2 of the ladle when the porous plug is attached to the ladle, to the bottom of the protruding rod guide recess 3a. Alternatively, a molten steel outflow groove 3b inclined toward the outer circumference is formed.

In the refractory 3 in which the protrusion rod guide concave portion 3a and the molten steel outflow groove 3b are formed, the protrusion rod guide concave portion 3a
Various shapes can be adopted as the shape of the concave part, such as a conical shape, a truncated conical shape, and a hemispherical shape, but it is preferable to use a conical concave part in order to be easy to manufacture and to prevent molten steel from pooling in the center of the concave part. In the case of a conical recess, the apex angle θ is set to 90 in order not to reduce the strength of the refractory 3 and to avoid significantly increasing the height of the refractory 3 protruding into the ladle.
A range of 120° to 120° is preferred.

Furthermore, the width B of the molten steel outflow groove 3b of the refractory 3 is such that the strength of the refractory 3 is not reduced too much and the molten steel is allowed to flow into the concave portion 3 of the refractory 3.
10 to 5 so that it can flow out more easily
It is preferable to set it in the range of 0 mm.

Reference numeral 4 denotes a holding hardware similar to a steel plate that holds the lower end and lower outer periphery of the refractory 3, and an inlet hole for inert gas to be blown into the molten steel is bored approximately in the center of the part that contacts the lower end of the refractory 3. A gas blowing pipe 5 is fixed to this inflow hole by means such as welding.

A protruding rod guide concave portion 3a and a molten steel outflow groove 3b are provided at this tip.
The porous plug according to the present invention, in which a porous refractory material 3 formed with The bottom surface of the molten steel outflow groove 3b of No. 3 is the same as the inner surface of the ladle or protrudes from the inner surface of the ladle.
It is installed and mounted as shown in the figure.

With this structure, when replacing the porous plug, the molten steel in the protruding rod guide concave portion 3a on the top surface of the refractory 3 of the porous plug flows out from the molten steel outflow groove 3b, and molten steel is deposited on the top surface of the porous plug. In other words, the recess 3 for the protruding rod guide of the refractory 3 of the porous plug
Since the ladle is tipped sideways and pierced by the protruding rod 6 as shown in Fig. 3 without being filled in, the protruding rod 6 is reliably guided by the protruding rod guide recess 3a. The refractory 2 of the ladle will not be damaged due to misalignment of the protruding position of the protruding rod 6, and the porous plug can be removed safely and reliably.

As detailed above, the porous plug according to the present invention has a refractory height slightly higher than that of a conventional porous plug, and a concave part for a protruding rod guide and a molten steel outflow groove at the tip of the refractory. Since it has a simple structure of just providing a , it can be manufactured easily and at almost the same cost as conventional porous plugs, and when a porous plug is punched out of a ladle with a protruding rod, it can be punched out without damaging the ladle. Therefore, its practical value is extremely large.

[Brief explanation of drawings]

Figure 1 is a vertical cross-sectional view showing a porous plug attached to a ladle, Figure 2 is an enlarged vertical cross-sectional view showing a conventional porous plug, and Figure 3 is a porous plug punched out of a ladle with a protruding rod. 4 is a perspective view of one embodiment of the porous plug according to the present invention; FIG. 5 is an enlarged longitudinal sectional view showing the porous plug shown in FIG. 4 installed in a ladle; FIG. It is. DESCRIPTION OF SYMBOLS 1... Iron skin, 2... Refractory material, 3... Porous refractory material, 3a... Recessed part for protruding rod guide, 3b... Molten steel outflow groove, 4... Holding hardware, 5... Gas blowing pipe, 6
... protruding rod, θ... apex angle of protruding rod guide concave portion 3a,
B... Width of the molten steel outflow groove 3b.

Claims (1)

[Claims for Utility Model Registration] 1. A protruding rod guide recess 3a is formed at the tip facing into the ladle, and the outer surface protruding from the inner surface of the ladle reaches the bottom of the protruding rod guide recess 3a. A porous refractory 3 in which a molten steel outflow groove 3b is formed horizontally or inclined toward the outer periphery is held at the other end by a holding metal fitting 4 to which a gas blowing pipe 5 is fixed. plug. 2. The porous plug according to claim 1, wherein the protruding rod guide recess 3a of the refractory 3 is a conical recess. 3. The porous plug according to claim 2, wherein the apex angle θ of the conical shape of the protruding rod guide concave portion 3a of the refractory 3 is 90° to 120°. 4 Width B of molten steel outflow groove 3b of refractory 3 is 10 to 50 mm
A porous plug according to any one of claims 1 to 3 of the utility model registration claims.