JP2001334361A - Device for protecting flowing-down molten metal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device for protecting the flowing-down molten metal with which the molten metal is blocked from the outer air with inert gas when the molten metal in a ladle is poured while flowing-down into a pouring tube from a nozzle and also, the state of the flowing-down molten metal stream can visually be observed. SOLUTION: (1) The protecting device for the flowing-down molten metal, is composed of the nozzle for making the molten metal flowing-down, a facing member which surrounds the molten metal stream flowing-down from the nozzle and is faced to the upper end surface from this upper part, while having the widening substantially including the upper end surface of the pouring tube in the air-tight state with the nozzle, and an inert gas feeding-out part for feeding out inert gas into the periphery of the nozzle or the molten metal stream through a porous material layer at the lower part of this facing member. (2) In the device (1), a pouring tube setting inert gas feeding-out part disposed so as to surround the molten metal stream at the upper part of the pouring tube and feeding out the inert gas from the inner periphery, etc., is attached.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technical field of casting a molten metal from an injection pipe to an ingot case or the like via a pipe in a ladle or the like when the molten metal is poured downward from a nozzle into the injection pipe. The present invention also relates to a molten metal protection device that shuts off molten metal from outside air with an inert gas and that can visually monitor the state of the molten metal flow.

[0002]

2. Description of the Related Art Conventionally, when a molten metal in a ladle or the like is poured downward into an injection pipe, the molten metal is shut off from outside air to oxidize the molten metal.
For the purpose of preventing nitrogen pickup, a refractory curtain is often used between the tapping nozzle at the bottom of the ladle and the injection pipe, and the curtain has been proposed to be improved in shape and the like for monitoring the pouring condition. ing. Also, Japanese Patent Application Laid-Open No. 9-1976
No. 0 is provided with a heat insulating plate horizontally at the lower end of the molten metal nozzle, and a plurality of gas ejection nozzles provided at equal intervals on the inner peripheral side of the ring of the cavity provided inside so as to surround the molten metal flow, A that produces a swirling flow surrounding the molten metal flow
We have proposed a balloon ring.

Japanese Patent Application Laid-Open No. 61-206559 discloses an annular pipe formed by bending a pipe and a disk-shaped shield plate fixed to the inner periphery of the pipe. A nozzle for flowing molten metal is penetrated through the shield plate. Piercing a large number of fumarole holes downward on the lower surface of the annular pipe, blasting an inert gas such as Ar from the fumarole,
A hollow annular body is disclosed in which the blast gas flows downward outside the upper end surface of the injection pipe. Also, Japanese Patent Application Laid-Open No. 56-1
Japanese Patent No. 9969 covers the upper and lower surfaces of a ring-shaped porous nozzle surrounding a molten metal flow with a sealing material, and opposes the molten metal flow from the inner periphery to blow out nitrogen gas or the like, and the injection flow shuts off the inside of the injection pipe from outside air. In addition, an apparatus has been proposed in which the jet stream is caused to collide with the molten metal stream to form an upward flow surrounding the molten metal stream.

[0004]

Although the use of the above-described fire-resistant curtain is advantageous in terms of shutting off the outside air at the time of pouring, it is difficult to monitor the state of pouring. There was a problem that the interruption was incomplete. The inability to monitor the pouring condition by monitoring or the like is a major obstacle to achieving safe and reliable pouring such as the occurrence of overflow. According to the experiments of the present inventors, the method of forming a gas curtain by a gas ejection nozzle disclosed in JP-A-9-19760, JP-A-61-206559, etc. is based on the fact that the ejected gas entrains the surrounding air. Leakage of air from between nozzles etc. (the molten metal flow generates a negative pressure in its vicinity due to suction action), contaminating the protective atmosphere with air, high-speed gas flow, and therefore a large amount of atmospheric gas And the molten metal stream are in contact with each other, so that it is difficult to obtain a sufficient blocking and protecting effect, for example, oxidation or the like occurs due to the purity of the inert gas or contamination of the protective atmosphere.

In the method using a porous nozzle described in Japanese Patent Application Laid-Open No. 56-19969, the upward flow is caused by air flow,
In other words, in order not to be affected by the wind, it is necessary to make the upward flow at a high flow velocity and thick, and therefore, a large amount of inert gas is required. Depending on the purity of the protective gas, oxidation may occur. SUMMARY OF THE INVENTION It is an object of the present invention to provide a protection device for a molten metal that has a high effect of blocking the atmosphere by suppressing the influence of wind and that can be monitored visually.

[0006]

Means for Solving the Problems The present inventors, through the casting of ultra-clean steel, ultra-low oxygen steel, ultra-low nitrogen steel, etc., protect a conventional flowing molten metal protection device and a pouring method using the same. The importance of grasping the imperfection and the state of pouring was found, and various experiments were conducted on the apparatus and method. As a result, a porous member is used as a method of delivering an inert gas, and a surrounding member is surrounded by the molten metal flow, and a facing member facing the upper end surface of the injection pipe from above and having a hermetic seal between the nozzle and the injection member. The present inventors have found out that the protective effect and the visualization of the pouring state can be visually monitored by using them together, and arrived at the present invention.

[0007] That is, the first aspect of the downflow molten metal protection device of the present invention is a nozzle which flows down the molten metal, and which surrounds the flow of the molten metal flowing down from the nozzle and substantially covers the upper end surface of the injection pipe which receives the flow of the molten metal. A porous material which is opposed to the upper end face from above, has an airtight space between the nozzle and the nozzle, and an inert gas below the opposed member and around the nozzle or the melt flow. It is a flowing-down molten metal protection device characterized by comprising an inert gas delivery section for delivering through a layer.

[0008] Further, the second invention provides the device of the first invention,
An injection pipe installation inert gas delivery section installed on the injection pipe is added. That is, a nozzle for flowing the molten metal,
Injection pipe installation installed above the injection pipe for receiving the flow of the molten metal flowing down from the nozzle and surrounding the molten metal stream, and delivering an inert gas through openings provided in at least one of the inner periphery and the upper and lower surfaces. Portion, surrounding the melt flow, facing the upper end surface from above with a spread substantially including the upper end surface of the injection pipe installation inert gas delivery portion, and airtight between the nozzle and the nozzle. And an inert gas delivery section for delivering an inert gas through a porous material layer to a lower portion of the opposed member and below the opposed member and around the nozzle or the molten metal flow. .

In the present invention, the inert gas is delivered through a porous material layer, that is, an infinite number of minute openings, grows into a gas mass, and excludes the atmosphere including the molten metal flowing down portion to be shut off. For this reason, the air does not entrain the atmosphere like the jet flow from the gas jet nozzle, there is no equivalent of air leakage between the gas jet nozzles, and the molten metal flow does not come into contact with the high-speed gas flow Therefore, a sufficient shut-off protection effect is realized, and the molten metal flow is kept to a minimum by oxidation by gas and pickup of nitrogen. As described above, since the inert gas mass delivered through the porous material layer of the present invention does not have a high velocity in a specific direction such as a jet flow from a gas jet nozzle, it is easily swept away by wind. Although it is easy, the opposing member of the present invention minimizes the influence of wind by forming a semi-closed space facing the injection pipe or the inert gas delivery section installed above the injection pipe and facing it from above. Stop at

[0010] In order to form an effective semi-closed space with the opening as a minimum and place the molten metal flow in the center thereof, the opposing member surrounds the molten metal flow and is installed at or above the injection pipe. The expansion relationship and the arrangement relationship should be such that the upper end face of the injection pipe installation inert gas delivery section to be formed has a spread substantially including the upper end face and is opposed to the upper end face from above. In particular, if the opposing member has a hanging part extending above the upper end of the injection pipe or the inert gas delivery part on the injection pipe around the periphery thereof so as to form a concave space below, the influence of wind is reduced. Can be lower. Further, since the facing member is made airtight between the nozzle and the nozzle, it is possible to prevent the atmosphere from being attracted by the suction action of the molten metal flow. Then, between the facing member and the injection pipe or the injection pipe-installed inert gas delivery section, it is possible to visually monitor the flow of the molten metal flowing down, and furthermore, the sound generated when the molten metal collides with the molten metal or the like in the injection pipe. It becomes a propagation path, and it is possible to grasp the flow-down state by this sound.

The operation and effect of the inert gas delivery section provided with the injection pipe in the second invention will be described. At the start of pouring, since the pipes and the like after the injection pipe are filled with air, a large amount of atmospheric gas is sucked from the molten metal flowing down, so that the inert gas delivered from the inert gas delivery section 7 above the semi-enclosed space is not filled. A large amount of outside air will be sucked over the upper edge of the injection tube 10 rather than the active gas. When the inert gas delivery section 11 is installed on the injection pipe 10 and the inert gas is delivered from a surface excluding its outer peripheral surface, the delivered gas is sucked, thereby preventing the suction of the outside air or Is suppressed.

Injection pipe installation The method of installing the inert gas delivery section 11 is simple in that it is placed on the injection pipe. In this case, the delivery of gas is limited to the inner circumference and the upper surface. Further, it is desirable that the gas is delivered from a porous material from the viewpoint of preventing air from being entrained. In addition, if a gas having a specific gravity of Ar greater than that of air is sent in advance as an inert gas, an effect that a part of a pipe line and the like after the injection pipe is replaced with this gas also occurs. That is, it is possible to easily supply a required gas amount to an appropriate place in advance or when necessary before and after the start of pouring. In addition, by adopting the injection pipe-installed inert gas delivery section, the total amount of the upper and lower portions of the inert gas delivered to the semi-enclosed space can be reasonably increased, and the opposed member and the injection pipe-installed inert gas delivery section can be provided. Thus, it is possible to suppress the influence of wind by increasing the blowing speed of the inert gas between the opposed parts, to secure a sufficient dimension between the opposed parts necessary for visual monitoring, and the like.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, the inert gas delivery section is formed in a ring shape or composed of a plurality of unit delivery sections, and the ring-shaped or plurality of unit delivery sections are arranged so as to surround a nozzle or a molten metal flow. In this case, the fresh inert gas that has been sent out generates a flow that wraps around the molten metal stream due to the suction action of the molten metal stream, thereby enhancing the blocking protection effect. In addition, if the periphery of the opposed member is formed as a hanging part as described above, the influence of the wind itself is further reduced, and in this case, a concave semi-closed part in which the inert gas delivery portion is surrounded by the hanging part. Providing at the top of the target space prevents the generation of a dead space that is not replaced by the inert gas, and the molten metal is conveniently wrapped with a fresh inert gas as the innermost layer.

Further, if one or both of the outer flange and the inner flange are provided at the lower end of the hanging part, it is less susceptible to the wind itself, and the molten metal protection device and the injection pipe or the installation of the injection pipe are inert. The flange portion and the injection pipe surely face each other up and down even with a slight misalignment with the gas delivery portion, and the semi-closed property is ensured. These enhance the shielding protection effect and contribute to the reduction of the consumption of inert gas.

The method of arranging the plurality of unit sending portions so as to surround the nozzle or the molten metal stream is preferable in that the manufacturing is easier than the ring-shaped sending portion which is somewhat difficult to manufacture. In addition, according to the investigation results by the examples, there was no difference in effect from the ring-shaped one when the eight or more were arranged at equal intervals on the circumference. If the inert gas delivery unit is removably attached to the ladle, etc., and removed when cleaning the nozzle (by spraying oxygen gas onto the nozzle inner surface, etc.),
This is advantageous because damage can be prevented. If the inert gas delivery section is made of a sintered material, it is convenient to easily control the characteristics related to the outflow of the inert gas such as porosity, and among them, those made of metal and those made of stainless steel are heat resistant. Excellent in durability.

[0016]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a device according to the present invention; FIG. Although the drawings are drawn in a sliding nozzle type, the present invention is not limited to this, and can be naturally applied to a stopper type. FIG. 1 is a cross-sectional view of an example of a molten metal protection device according to the present invention installed on the bottom of a ladle. The ladle 1 has a nozzle 2 at the bottom thereof, and the nozzle 2 is slid in the direction of arrow X by a hydraulic drive mechanism (not shown) to cause the molten steel flow 9 to flow down as shown. During the flow, the nozzle 2 and the injection pipe 10 are substantially concentric.

The falling molten metal protection device according to the present invention has a width surrounding the nozzle 2 for flowing the molten metal, the molten metal flow 9 flowing down from the nozzle, and substantially including the upper end surface of the injection pipe 10 for receiving the molten metal flow 9. The inert gas is passed through the porous material layer to the upper end face from above, the airtight state between the nozzle 2 and the opposing member 8a and the lower part of the opposing member 8a and around the molten metal flow 9. Inert gas sending section 7 to send
Etc.

The inert gas delivery section 7 has a cavity 3 formed therein and is provided with a ring 4 surrounding the molten metal flow 9 and at a plurality of circumferential locations on the lower surface of the ring 4 communicating with the cavity 3 at equal intervals. The porous cylindrical pellet 5 made of a stainless steel sintered body and the cavity 3 of the ring 4 fitted into each of the openings respectively.
The pellet 5 constitutes a unit sending section. In this embodiment, the number of the unit sending sections 5 is eight. The opposing member 8a is composed of a hanging part extending upwardly above the upper end of the injection tube and a flange part 8 'extending inward and outward at the lower end of the hanging part so as to form a concave space below. The upper portion of the facing member 8a is hermetically sealed with the nozzle 2 via the ring 4. The facing member 8 a is detachably attached to the nozzle 2 together with the ring 4. However, the facing member 8a can be made airtight with the nozzle 2 by directly attaching it to the ladle 1.

In the above-mentioned molten metal protection device, the opposing member 8a is concentric with the injection pipe 10 during pouring,
It is brought to a position where the lower end of “a” is higher than the upper end of the injection tube 10 by the dimension Y. The inert gas such as Ar sent from the air supply pipe 6 flows downward from above in each pellet 5 through the cavity 3 and hangs down without becoming a jet like a gas stream from a gas ejection nozzle. It is delivered to the upper part of the space surrounded by the opposing member 8a and fills this part, and finally fills the semi-closed space surrounded by the opposing member 8a and the injection pipe 10 while excluding outside air. Since the space is semi-closed, the inert gas in the space is suppressed from being blown off by external wind.

The flange portion 8 'having a sufficient width dimension is
Even before pouring, that is, when the nozzle 2 and the injection pipe 10 are misaligned, the semi-closed space is maintained in a semi-closed state.
Desirably, in this state, Ar gas or the like is supplied to replace the gas in the semi-closed space, and then the nozzle 2 is moved in the X direction. Then, the flow of the molten metal starts. Due to the flow of the molten metal, the upper part of the semi-closed space has a negative pressure with respect to the outside air. However, since the space between the opposed member 8a and the nozzle 2 is made airtight, there is no suction of the outside air and contamination of the inert atmosphere. Does not occur. Further, the molten metal stream 9 flows down to the injection pipe 10 while being covered with fresh inert gas sent from the unit sending section 5 arranged so as to surround the molten metal stream 9 by its suction action.
The presence of the dimension Y between the opposed portions enables visual monitoring of the situation of the molten metal 9 flowing down, and a propagation path of a sound generated when the molten metal stream 9 collides with the molten metal or the like in the injection pipe 10 is formed.
It is also possible to grasp the flow condition by this sound.

In this embodiment, the inert gas inlet 7 and the opposing member 8a are directly attached to the nozzle 2 to reduce the size and weight of the entire apparatus while reducing the volume of the semi-closed space and the area of the opening of the dimension Y. By suppressing the increase, the opposing member 8a is formed in a tapered shape that opens downward, so that the opening of the dimension Y is located far from the molten metal flow 9 while maintaining high closing performance, thereby preventing a decrease in the protection effect on the molten metal flow 9. It has features such as
In the present embodiment, there is a small dead space above the unit sending section 5, that is, in the inner peripheral portion of the ring 4. However, since this space has a small volume, the unit sending section 5 is difficult to manufacture. It was installed on the lower end surface of the ring 4. FIG. 2 is an example in which the volume of the concave space formed by the hanging part of the opposing member 8a is reduced as compared with that of FIG.

FIG. 3 is an explanatory view of an example in which an injection pipe installation inert gas delivery section 11 is added to the downflow molten metal protection apparatus of FIG. The injection pipe installation inert gas delivery section 11 is installed on the injection pipe 10 so as to surround the molten metal flow, and sends out the inert gas through an opening provided on the inner periphery. In this example, the opening provided on the inner periphery was made of a plurality of porous material pellets. In this embodiment, prior to the injection of the molten metal, an inert gas is supplied from the injection pipe installation inert gas delivery unit 11 as an inert gas.
r A gas having a specific gravity greater than that of air is sent out in advance, and a part of a pipe line and the like after the injection pipe can be replaced with these gases. By making all or a part of the gas delivered from the injection pipe installation inert gas delivery unit 11 prevent or suppress the suction of outside air, the opening of the dimension Y during continuous pouring is necessary for visual monitoring. There are effects such as sufficient spacing, or increasing the inert gas blowing speed from the opening to suppress the influence of wind.

FIG. 4 shows that the lower end of the nozzle is lowered by using a flat plate 8b as the opposing member, thereby lowering the flow drop of the molten metal at that position, and thereby reducing the exposed surface area and the suction effect on the atmosphere gas, thereby shielding the nozzle. This is an example in which the protective action is enhanced. In addition, the injection pipe installation inert gas delivery unit 11 shown in FIG.
Can be used in combination with the molten metal protection device shown in FIG. 2 or FIG.

[0024]

As described above, according to the present invention, there is provided an opposing member having a specific shape and arrangement, and an inert gas transmitting apparatus for transmitting an inert gas to a specific position of the opposing member through a porous material layer. Part, the entrainment of outside air into the inert gas,
The present invention prevents the intrusion of outside air and the influence of wind due to the suction action of the molten metal flow, and enables the molten metal flow to be highly shielded and protected from the atmosphere and to monitor the state of the molten metal.
According to the present invention, the safety of ultra-clean steel, ultra-low oxygen steel, ultra-low nitrogen steel, etc. is reduced by suppressing the influence of wind, etc., and maintaining a high air-blocking effect. It has become possible to realize reliable pouring.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing another embodiment of the present invention, in which the volume of the concave space is reduced.

FIG. 3 is an explanatory view showing an example in which an injection pipe inert gas delivery unit 11 is added to the downflow molten metal protection device of FIG. 1;

FIG. 4 is a cross-sectional view showing another embodiment of the present invention, in which the lower end position of the nozzle is lowered by making the facing member 8 flat, and the exposed surface area of the molten metal and the suction action are reduced.

[Explanation of symbols]

1. Ladle, 2. Nozzle, 3. Cavity, 4. Ring, 5. 5. Pellet (unit sending unit) 6. supply pipe; Inert gas delivery section, 8a. Opposing member (having hanging part), 8b. Opposing member (flat plate: no hanging part), 8 '. Flange,
9. 10. Downflow molten metal; Injection tube, 11. Injection tube installed inert gas delivery section, X. Moving direction, Y. Size

Claims (4)

[Claims] 1. A nozzle for flowing a molten metal, surrounding the molten metal flow flowing down from the nozzle, facing the upper end surface from above with a spread substantially including an upper end surface of an injection pipe for receiving the molten metal flow. A counter member which is hermetically sealed between the nozzle and the nozzle, and an inert gas sending portion for sending an inert gas through the porous material layer to below the counter member and around the nozzle or the melt flow. A downflow molten metal protection device. 2. A nozzle for flowing the molten metal, and is installed above an injection pipe for receiving the molten metal flowing down from the nozzle so as to surround the molten metal flow, and is inactive through an opening provided on at least one of the inner periphery and the upper and lower surfaces. An injection pipe installation inert gas delivery section for delivering gas, surrounding the molten metal stream, facing the upper end face from above with a spread substantially including an upper end face of the injection pipe installation inert gas delivery section; A counter member which is hermetically sealed between the nozzle and the nozzle, and an inert gas sending portion for sending an inert gas through the porous material layer to below the counter member and around the nozzle or the melt flow. A downflow molten metal protection device. 3. The opposed member has a hanging part extending above an upper end of an injection pipe or an inert gas delivery part provided with an injection pipe around the circumference so as to form a concave space below the opposite member. The falling molten metal protection device according to claim 1 or 2, which is provided above the concave space. 4. The inert gas delivery section comprises a ring or a plurality of unit delivery sections, and the ring or the plurality of unit delivery sections surround a nozzle or a molten metal stream. Downstream molten metal protection device.