JPH09155535A - Hole force opening method for molten metal outflow hole and hole force opening device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to prevent the contamination of molten metal as packing sand is not used in a molten metal outflow hole by detaching an upper part closing plug from the molten metal outflow hole by a pushing-up rod moved upward by a lower part closing plug and opening the hole of a sliding type opening/closing device. SOLUTION: When a rod 8 is moved upward to the sliding surface of a stationary plate 10 and a sliding plate by a hydraulic cylinder 7, the lower closing plug 4 pushes up the pushing-up rod 6 and comes into contact with the upper closing plug 3. The pushing-up rod 6 rises further and the upper closing plug 3 floats in the molten steel. The molten steel flows successively into an upper nozzle 9. The top end face of the lower closing plug 4 is aligned to the front surface of the sliding plate 11 and the sliding plate 11 is rotated around the axial center A by the hydraulic cylinder 7, by which the outflow hole of the stationary plate 10 and a collector nozzle 12 are mated to allow the molten steel to flow out. As a result, the packing sand is not used for the molten metal outflow hole and, therefore, their is no contamination of the metal by the packing sand and the mechanical opening by the hole opening device is made possible.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molten metal outflow when a molten metal outflow hole provided in a bottom portion of a ladle or the like as a molten metal storage container is made to be in an open state so that molten metal flows out. The present invention relates to a forced opening method and a forced opening device that allow easy opening of holes.

[0002]

2. Description of the Related Art In a molten metal storage container, the molten metal is held in the storage container for a required time in the step of transporting the stored molten metal to a predetermined position or treating a predetermined amount, and then the molten metal is transferred to the bottom portion in the next step. Flow out through the molten metal outflow hole. If the next step is casting, the molten metal will be poured into casting equipment. As shown in FIG. 7, the molten metal outflow hole has an upper nozzle 9, a fixing plate 10 fitted to a lower portion of the upper nozzle 9,
A sliding plate 11 that slides under the fixed plate 10,
And a collector nozzle 12 closely attached to the bottom of the sliding plate 11. This molten metal outflow hole is provided to prevent the molten metal from being solidified and sealed.
Generally, the filling sand 4 is used as the filling, and after the molten metal is held in the container for a predetermined time, the sliding plate 11 is rotated or slid at the time of opening to drop and discharge the filling sand 4 from the molten metal outflow hole. After that, the molten metal is allowed to flow out of the container (this is called "natural opening"). Silica sand is generally used as the filling sand 4, but the filling sand 4 is sintered depending on various conditions such as the type of silica sand, the molten metal temperature, the holding time of the molten metal, and the preheating time of the molten metal container. In some cases, the effect of the molten metal may be insufficient because the molten metal may float on the surface of the molten metal, or the molten metal may penetrate into the sand filling 4.
In this case, an oxygen lance is inserted into the molten metal outflow hole from the lower side of the container bottom to oxidize and melt the sand 4 and the solidified metal with oxygen to forcibly flow out the molten metal in the container. (This is called "oxygen cleaning").

Conventionally, it has been a problem to improve the natural sand porosity by improving the sand filling, and various proposals have been made. In Japanese Patent Laid-Open No. 62-244570 (hereinafter, referred to as "Prior Art 1"), the purity of silica sand in the filling sand, the content of alumina as an impurity, and the size configuration are specified to prevent oversintering and molten steel. It is disclosed that a high natural open area ratio is obtained by preventing the penetration of molten metal such as, for example, into the clogging sand. In JP-A-6-71424 (hereinafter, referred to as "Prior Art 2"), a mixture of chrome ore and silica sand or silica and graphite is used as stuffing sand, and the mixing ratio and size composition of each mixture are specified to melt. It is disclosed that silica sand or a silica-like glass-like adhesive layer is interposed in the gap of high-temperature chrome ore to prevent molten metal (molten steel) from penetrating into the clogging sand to obtain a high natural porosity. ing.

As a technique which does not use clogging sand, it has been proposed to use a refractory plug in Japanese Patent Laid-Open No. 60-255259 (hereinafter referred to as "Prior Art 3"). As shown in FIG. 6 (1), this technique is applied to a nozzle receiving brick 13 installed so as to match a sliding nozzle having a fixed plate 10 and a sliding plate 11 provided at the bottom of a molten metal storage container. A closure plug 20 that fits over the upper nozzle 9 is provided. Fig. 5 when opening
As shown in (2), the piston 21 is pushed up by the gas generating pressure of the gas generating substance packed in the cylinder 22 to open the hole. In addition, instead of the gas generation pressure of the gas generating substance, hydraulic pressure or electric power can be applied.

[0005]

In the prior arts 1 and 2 using packed sand which have been conventionally performed, as described in the examples, the porosity is not 100%, and therefore,
It was necessary to perform oxygen cleaning with an oxygen lance when the hole was not opened. Therefore, iron oxide is generated during oxygen cleaning, and the slag containing iron oxide that has flowed out into the container on the side where the molten metal is injected serves as an oxygen source, which oxidizes the molten metal, leading to deterioration in quality and reduction in yield. It was Also, in Prior Art 3, the use of gas generants such as Na ₃ N and Na ₂ CO ₃ in a container holding molten steel is a natural reaction of the gas generant caused by heat from the molten metal container. Cannot be controlled, and safety remains a problem, and safety and reliability remain in terms of impact on the refractory that constitutes the sliding nozzle when gas is generated.
By the way, Na ₃ N and Na ₂ as gas generating substances
Regarding CO ₃ , the heat resistance of Na ₃ N is 400 ° C or lower,
The heat resistance of Na ₂ CO ₃ is in the low temperature range of 800 ° C. or lower.
Further, when hydraulic pressure or an electric motor is used, these are consumable items that are consumed by a single hole-opening operation, and there is a problem that the cost is large.

The present invention provides a low-cost and high-efficiency forcible hole-opening method and a forcible hole-opening device for surely opening a molten metal outflow hole provided at the bottom of a ladle or the like as a molten metal storage container. The purpose is to do.

[0007]

According to the method for forcibly opening a molten metal outflow hole of the present invention, the lower portion of the molten metal outflow hole provided at the bottom of the molten metal storage container is disposed outside the bottom of the molten metal storage container. Is closed by a vertically movable lower closing plug provided in the sliding type opening / closing device, and a push-up rod is inserted in the upper portion of the lower closing plug, and the upper portion of the molten metal outlet hole is closed by the upper closing plug. When the molten metal stored in the molten metal storage container is caused to flow out through the molten metal outflow hole, it is lifted up to at least the sliding surface of the sliding type opening / closing device. The upper closing plug is disengaged from the molten metal outflow hole by a push-up rod that is lifted by, and then the sliding type opening / closing device is opened.

Further, in the forced opening device for molten metal outflow holes of the present invention, sliding is provided outside the bottom of the molten metal storage container for closing the lower part of the molten metal outflow hole provided in the bottom of the molten metal storage container. A vertically movable lower closing plug provided in a switchgear, an upper closing plug that closes the upper portion of the molten metal outflow hole, and a push-up that is inserted into the molten metal outflow hole that is closed by the lower closing plug and the upper closing plug. It is characterized by having a rod and a drive mechanism for vertically moving a lower closure plug provided in the sliding type opening / closing device. According to the present invention, the closing plug is forcibly opened without using clogging sand, so that the molten metal outflow hole can always be reliably opened.

[0009]

1 is a cross-sectional view showing an embodiment of the present invention, which is applied to a rotary nozzle which is a rotary sliding type opening / closing device, and an example in which molten steel is applied as molten metal. Indicates. In FIG. 1, 9 is an upper nozzle which forms a molten metal outflow hole. A fixed plate 10 is fitted to the lower portion of the upper nozzle 9. Reference numeral 11 denotes a sliding plate, which is slidably arranged below the fixed plate 10.
Reference numeral 12 is a collector nozzle, which is in close contact with the outflow hole of the sliding plate 11 so as to coincide therewith. Reference numeral 13 denotes a nozzle receiving brick, which is installed at the bottom of, for example, a ladle which is a molten metal storage container, and is equipped with an upper nozzle 9. Reference numeral 14 is an iron skin at the bottom of the molten metal container. Here, 2 is a rotary nozzle, and the sliding plate 11 rotates around the axis A as in the conventional case.

The molten steel in the molten metal container rotates the sliding plate 11 to open the molten metal outflow hole formed by the upper nozzle 9 and the fixed plate 10 corresponding thereto.
By aligning the outflow hole of No. 2 with the outflow hole of the sliding plate 11, the outflow through the upper nozzle 9 → the outflow hole of the fixed plate 10 → the outflow hole of the sliding plate 11 → the collector nozzle 12 flows out to the outside. The sliding plate 11 has two or more outflow holes. The forced opening device 1 is provided below one outflow hole of the sliding plate 11. The forced opening device 1 has a hydraulic cylinder 7 as a drive mechanism for driving a rod 8 which is expandable and contractible in the axial direction of the molten metal outflow hole. Further, at the tip of the rod 8, there is directly connected a lower closure plug 4 that closes and closes the outflow hole of the sliding plate 11 for preventing molten steel from flowing out. The lower closure plug 4 slides in the outflow hole of the sliding plate 11 as the rod 8 expands and contracts, and can slide into the upper nozzle 9 if a drive mechanism having a long stroke is used.

Next, a procedure for assembling the forced hole forming device having the above-described structure will be described. The molten metal storage container, for example, a ladle is tilted so that the molten metal outflow hole of the rotary nozzle 2 becomes substantially horizontal, and the outflow hole of the fixed plate 10 and the outflow hole of the sliding plate 11 in which the collector nozzle 12 is arranged are arranged. Together, the push-up rod 6 is inserted into the upper nozzle 9 and set. After that, the sliding plate 11 is rotated about the rotation axis A by a rotation mechanism (not shown), and the outflow hole of the fixed plate 10 and the outflow hole in which the forced opening device 1 of the sliding plate 11 is preset are aligned. . The forced opening device 1 is installed at the bottom of the ladle by a mounting jig (not shown). After that, the ladle is rotated again, and the upper closure plug 3 is placed in contact with the upper portion of the upper nozzle 9. In order to ensure the closure of the upper nozzle 9 by the upper closure plug 3, it is desirable to fix the contact surface between the upper closure plug 3 and the upper nozzle 9 with the castable 5. At this time, the push-up rod 6 does not need to be vertical, and may be set in the upper nozzle 9, and the push-up rod 6 and the upper closure plug 3 need not be in contact with each other. The molten steel received from the converter or the electric furnace in this state is subjected to secondary refining in a secondary refining facility as required. After the processing such as secondary refining is completed, the ladle is conveyed to the pouring position of a continuous casting machine or the like, and the ladle is installed at a predetermined position for casting.

Next, a method of opening the molten steel from the forced-hole forming device 1 when the molten steel is flown out from the molten metal container will be described with reference to FIG.
This will be described with reference to FIG. From the state shown in FIG. 1 in which the molten steel is stored in the molten metal storage container, the sliding plate 11 is slid about the rotation axis A so that the outflow hole of the fixed plate 10 and the outflow hole of the sliding plate 11 are separated from each other. In order to flow out the combined molten steel, first, the hydraulic cylinder 7 is driven and the rod 8
Is raised to at least the sliding surface where the fixed plate 10 and the sliding plate 11 are in contact with each other. Then, as shown in FIG. 2, the push-up bar 6 is pushed up by the lower closure plug 4 fixed to the end of the rod 8. Then, the push-up bar 6 pushed up contacts the upper closure plug 3. The push-up bar 6 is further raised and, as shown in FIG.
Is separated from the upper nozzle 9 and floated in the molten steel. The molten steel flows into the upper nozzle 9 at the same time as the upper opening of the upper nozzle 9. After removing the upper closure plug 3 from the upper nozzle 9,
As shown in FIG. 4, if the upper end surface of the lower stopper 4 and the upper surface of the sliding plate 11 are not the same, the hydraulic cylinder 7 is
The operation of moving the rod 8 is performed, for example, to lower the lower closure plug 4 so as to be on the same plane. At that time, since the lower closure plug 4 is in close contact with the outflow holes of the upper nozzle 9, the fixed plate 10 and the sliding plate 11, even if molten steel flows into the upper nozzle 9 and further the fixed plate 10, the lower closure plug 4 is closed. Since molten steel is not inserted between the plug 4 and the outflow hole, the lower closure plug 4 can be easily lowered.

Thereafter, as shown in FIG. 5, the sliding plate 11 is rotatably slid about the axis A, so that the outflow hole of the fixed plate 10 and the outflow hole of the sliding plate 11 in which the collector nozzle is arranged are arranged. By combining, the push-up bar 6 is dropped into the steel receiving container, and molten steel in the molten metal storage container is injected through the upper nozzle 9, the outflow hole of the fixed plate 10, the outflow hole of the sliding plate 11 and the collector nozzle 12. To be done. At that time, the lower closure plug 4 moves the sliding plate 11
The upper surface of the lower stopper 4 must be lower than the sliding surfaces of the fixed plate 10 and the sliding plate 11 so that the rotation of the sliding plate 11 is not hindered. In order to prevent this, the upper surface of the lower stopper 4 should be flush with the sliding surfaces of the fixed plate 10 and the sliding plate 11, that is, It is desirable that the upper end surface is lifted to the same plane as the upper surface of the sliding plate 11 so that the upper closing plug 3 is disengaged from the upper nozzle 9. After the upper closing plug 4 is detached, the molten steel flows into the outflow hole, and the inflowing molten steel begins to solidify. Therefore, it is necessary to immediately flow out the molten steel. Further, in the above-described embodiment, the method of rotating the sliding plate 11 (rotary nozzle) has been described, but in the case of the method of linearly moving the sliding plate 11 (sliding nozzle), the sliding plate 11 moves transversely. However, the present invention can be applied similarly to the above embodiment.

[0014]

EXAMPLES In the forced opening device of the present invention, the push-up rod was made of steel, and a hydraulic cylinder was used as a drive mechanism.
It was applied to a rotary nozzle type outflow hole at the bottom of a ladle with a capacity of 250 tons. The dimensions of each part of the member were as follows. The inner diameter of the bottom of the upper nozzle is 80 mmφ and the length is 36.
The pushing rod has a diameter of 30 mm and a length of 500 mm. The stroke of the hydraulic cylinder is 80 mm.
Silica sand was used as the filling sand. And, the casting results of 1000 charges are shown in Table 1. Table 1 also shows the results obtained by the conventional method at the same time. The average temperature of molten steel when receiving steel is 163.
The molten steel residence time in the ladle is 40 to 70 minutes at 0 ° C. According to the present invention, the opening ratio was 100% without oxygen cleaning. On the other hand, in the conventional method, 24 charges did not open naturally, and oxygen cleaning was performed. Table 2 shows the analysis results of the component analysis samples collected from the molten steel and the outflow holes in the ladle, and the component analysis samples collected from both the cast pieces after casting by the continuous casting machine. According to the present invention, there was almost no difference in composition between the molten steel in the ladle and the cast slab.

[0015]

[Table 1]

[0016]

[Table 2]

[0017]

As described above, according to the present invention, the molten metal outflow hole can be mechanically opened at the time of opening without using clogging sand, and the molten metal outflow hole can be opened at the time of opening. Since a different outflow hole is used, the opening device can be used repeatedly. Since it can be installed at low cost and does not need to use clogging sand, there is no need to worry about contamination of molten metal by clogging sand,
Also, there is no concern that clogging sand will fall to the lower collector nozzle, long nozzle, etc. where molten metal flows out. It is not necessary to particularly consider the shape of the lower nozzle such as the collector nozzle or the long nozzle, and the shape can be made simple so that the cost of the refractory material can be reduced, and thus the industrially useful effect is brought about.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment in which the present invention is applied to a rotary nozzle.

FIG. 2 is a cross-sectional view showing the progress of the method for forcibly opening molten metal outflow holes according to the present invention.

FIG. 3 is a cross-sectional view showing the progress of the method for forcibly opening molten metal outflow holes according to the present invention.

FIG. 4 is a sectional view showing the progress of the method for forcibly opening molten metal outflow holes according to the present invention.

FIG. 5 is a sectional view showing the progress of the method for forcibly opening molten metal outflow holes according to the present invention.

FIG. 6 is a cross-sectional view showing a nozzle closed state and a nozzle open state according to an embodiment of the prior art.

FIG. 7 is a sectional view showing another embodiment of the prior art.

[Explanation of symbols]

 1 Forced Opening Device 2 Rotary Nozzle 3 Upper Closing Plug 4 Lower Closing Plug 5 Castable 6 Push-up Rod 7 Hydraulic Cylinder 8 Rod 9 Upper Nozzle 10 Fixed Plate 11 Sliding Plate 12 Collector Nozzle 13 Nozzle Brick 14 Iron Crust

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takashi Itakura 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Inside Nihon Steel Pipe Co., Ltd. (72) In-house Hironori Yamamoto 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nippon Steel Tube Co., Ltd.

Claims (2)

[Claims] 1. A lower part of a molten metal outflow hole provided at the bottom of a molten metal storage container is closed by a vertically movable lower closure plug provided in a sliding type opening / closing device disposed outside the bottom of the molten metal storage container. The molten metal outflow hole, the push-up rod is inserted in the upper portion of the lower closure plug, and the molten metal stored in the molten metal storage container in which the upper portion of the molten metal outflow hole is closed by the upper closure plug. At the time of flowing out from the molten metal outflow hole, the upper closing plug is detached from the molten metal outflow hole by a push-up rod which is raised by at least the sliding surface of the sliding type opening / closing device and is raised by the lower closing plug provided in the sliding type opening / closing device. Then, a forced opening method for the molten metal outflow hole is characterized in that the sliding type opening / closing device is then opened. 2. A vertically movable lower closure plug provided in a sliding type opening / closing device arranged outside the bottom of the molten metal storage container for closing the lower part of the molten metal outflow hole provided in the bottom of the molten metal storage container. An upper closing plug that closes the upper portion of the molten metal outflow hole, a push-up rod that is inserted into the molten metal outflow hole that is closed by the lower closing plug and the upper closing plug, and a lower closing plug that is provided in a sliding type opening / closing device And a driving mechanism for vertically moving the molten metal outflow hole.