JP6187773B2 - Sliding nozzle device for molten metal holding container and method for pouring molten metal from this device - Google Patents

Description

  The present invention relates to a sliding nozzle device for a molten metal holding container and a method for pouring molten metal from the sliding nozzle device, and particularly proposes a technique effective for preventing the non-opening phenomenon of the sliding nozzle.

  Some molten metal holding containers such as tundish and ladle have a sliding nozzle at the bottom. This sliding nozzle is generally used to prevent the molten metal (hereinafter referred to as an example of “molten steel”) from solidifying in the nozzle hole to become a non-open state until the start of pouring of molten metal such as casting. Filled with sand. In this case, the sliding nozzle is closed after the packed sand is discharged in the casting (ingot-making) process or after the molten steel is injected into the mold. Then, when the sliding nozzle is opened again after moving to the next injection mold, sometimes at least a part of the molten steel remaining in the nozzle hole of the sliding nozzle is solidified, so that the sliding plate may be slid. May not open naturally. In such a case, it is necessary to perform a forced opening process by blowing oxygen gas (oxygen cleaning). However, when such an oxygen cleaning operation is performed, a problem of inclusion generation may occur. Further, even if such an oxygen cleaning operation is performed, there is a case where the opening does not occur and the casting is stopped.

  On the other hand, the following Patent Documents 1 and 2 have proposed a sliding nozzle device composed of a plate having a three-layer structure. Among them, Patent Document 1 discloses an inert gas bubbling from a slidable middle-layer sliding plate. In addition, in Patent Document 2, the inert gas is bubbled from the lower fixed plate to prevent the above-described non-opening due to the blockage. That is, these prior arts perform Ar gas bubbling from the sliding plate and the lower fixed plate until the sliding nozzle is "opened" after the sliding nozzle is "closed", It prevents the molten steel in the nozzle hole from solidifying and prevents it from becoming non-open when re-pouring.

JP 07-80611 A JP-B 63-56023

  In the case of the sliding nozzle device formed by combining the three-layer plates disclosed in Patent Documents 1 and 2, even if inert gas bubbling is performed from either the middle-layer sliding plate or the lower-layer lower fixed plate The non-opening inevitably occurs at a certain frequency. The inventors investigated the cause, and in Patent Document 1, the upper and lower sides of the molten steel passage (nozzle hole) of the sliding plate are closed when the middle sliding plate is in the closed position. There is a problem that the remaining molten steel solidifies and becomes an obstacle to the outflow of molten steel at the time of reopening.

  Further, the technique disclosed in Patent Document 2 does not leave molten steel in the molten steel passage (nozzle hole) of the sliding plate portion as described above, but it extends from the middle sliding plate to the upper upper fixing plate. Since the space of the molten steel passage (nozzle hole) in the plate is relatively narrow, the heat removal is large, and the replacement of molten steel is insufficient. Therefore, the technique disclosed in this document has a problem that solidification of residual molten steel in the passage cannot be completely prevented even if bubbling is performed.

  An object of the present invention is to propose an effective technique for preventing clogging of a nozzle hole accompanying solidification of residual molten steel that can occur after the filling sand is discharged or after the molten steel is poured.

As a result of diligent research for overcoming the above-mentioned problems of the prior art and realizing the above object, the inventors have arrived at the present invention according to the following configuration.
That is, the present invention is arranged under the upper nozzle in the bottom portion of the molten metal holding container, and comprises a combination of upper and lower fixed plates and a sliding plate that is movably held between them. In these sliding nozzle devices, these plates have nozzle holes of substantially the same diameter communicating with each other in the open position.
The nozzle hole of the sliding plate is provided with a diameter- expanding portion that expands downward at a position corresponding to the rear end side when the plate moves in the closing direction at a lower portion on the side in contact with the upper surface of the lower fixed plate. On the other hand, the nozzle hole of the lower fixed plate is provided with an enlarged diameter- expanding portion at an upper portion on the side in contact with the lower surface of the sliding plate at a position corresponding to the moving direction side of the sliding plate, and The enlarged diameter portions provided on the sliding plate and the lower fixed plate are elliptical shapes having different planar shapes, and the enlarged diameter portion of the lower fixed plate is larger than the enlarged diameter portion of the sliding plate. Is bigger than
A gas blowing plug is provided on the upper surface of the sliding plate in contact with the lower surface of the upper fixed plate at a position facing the nozzle hole of the upper fixed plate in the closed position after the sliding plate is moved. This is a sliding nozzle apparatus for a molten metal holding container.

Further, according to the present invention, when the molten metal in the molten metal holding container is poured into the dispensing container by using the sliding nozzle device according to claim 1, when the nozzle hole is closed at the end of the molten metal pouring, although in between the nozzle hole of the nozzle hole and a sliding plate of the fixing plate in the closed state of the nozzle holes with each other are not in communication with, between the nozzle hole of the nozzle hole and the lower fixed plate of the sliding plate, the sliding The nozzle hole of the plate is provided with a widening portion that expands downward at a position that contacts the rear end when the plate moves in the closing direction, on the lower side that is in contact with the upper surface of the lower fixed plate. the nozzle hole of the fixed plate on the side of the upper in contact with the lower surface of the sliding plate, through the respective enlarged diameter portion which enlarged diameter portion of the upper extent is provided in a position which corresponds moving direction side of the sliding plate With the condition that viewed communicating rather guide, by the the state Turkey be held down to 10 seconds the movement of the sliding plate, to discharge the molten metal remaining in the nozzle hole of at least the sliding plate We propose a method for pouring molten metal from a sliding nozzle device for molten metal holding containers.

According to the sliding nozzle device for a molten metal holding container according to the present invention having the above-described configuration and the molten metal pouring method performed using the same, the blockage at the time of re-pouring from the sliding nozzle often seen in conventional devices ( Non-opening) can be effectively prevented, and a natural aperture ratio close to 100% is exhibited. In particular, even if it is a three-layer sliding plate device, molten steel is not left in the nozzle hole of the middle-layer sliding plate when it is closed, and solidification does not occur. Therefore, it is possible to efficiently and reliably prevent the non-opening when the sliding nozzle is continuously opened (re-pouring operation).
Therefore, according to the present invention, it is not necessary to perform forced opening by oxygen blowing (oxygen cleaning) which is required by causing non-opening, so that the casting operation can be performed more safely, and inclusions in molten steel Can be prevented from increasing.

It is sectional drawing of the sliding nozzle apparatus which concerns on this invention. It is a basic diagram which shows the detail of each plate shape of a sliding nozzle apparatus. It is a basic diagram which shows the motion of each plate of the sliding nozzle apparatus which concerns on this invention. It is explanatory drawing of the casting work flow at the time of ingot formation in a prior art example, a comparative example, and an invention example.

  FIG. 1 is a sectional view showing a sliding nozzle device according to the present invention. In this figure, 1 shown in the figure is a sliding nozzle device provided at the bottom of the molten metal holding container 2, and an upper nozzle 3 in the molten metal holding container 2 and a lower nozzle (not shown) connected to an ingot forming / casting device (not shown). (Collector nozzle) 4 is arranged in a state of being sandwiched between.

  The sliding nozzle device 1 includes, from above, an upper fixed plate 5 positioned immediately below the upper nozzle 3, a sliding plate 6 positioned immediately below and sliding in a horizontal direction, and a lower fixed plate 7 positioned directly below the upper fixed plate 5. It has a three-layer structure.

  In this sliding nozzle device, the sliding plate 6 sandwiched between the upper and lower fixed plates 5 and 7 is opened and closed by a driving cylinder 8 attached to one end thereof. In addition, the sliding speed (about 50 to 300 mm / sec), sliding stroke (over 0 to full stroke), stop time (about 1 to 10 seconds), etc. can be adjusted and supported to be slidable in the horizontal direction. ing.

  The characteristic configuration of the sliding nozzle device according to the present invention is that the molten steel is poured into a ladle, a mold, a tundish, etc. following the discharge operation of the packed sand filled in the nozzle holes of the upper nozzle 3 and the upper fixing plate 5. When pouring into the discharge container, in particular, the molten steel is left in the nozzle holes 6a, 7a of the sliding plate 6 and the lower fixing plate 7 without being discharged (discharged) and cannot be completely discharged. It is in the point made into the structure prevented by adoption of a pair of enlarged diameter part mentioned later.

  On the other hand, for the molten steel in the nozzle hole 5a in the upper fixing plate 5, when the nozzle hole 5a of the upper fixing plate 5 and the nozzle hole 6a of the sliding plate 6 are not in communication (closed state), By blowing argon gas for bubbling from a gas blowing plug 9 having an upward opening structure provided in the sliding plate 6, the molten steel in the nozzle hole 5a of the upper fixed nozzle is constantly stirred to prevent solidification, It has a configuration that allows smooth reopening of the nozzle holes.

  In the present invention, the nozzle hole 6a of the sliding plate 6 and the nozzle hole 7a of the lower fixing plate 7 are formed in the following shapes in order to prevent the generation of residual molten steel due to solidification in the nozzle hole. That is, each of the plates 5, 6, and 7 basically has nozzle holes of substantially the same diameter communicating with each other in the open position. In addition, the nozzle hole 6a of the sliding plate among these nozzle holes has a rear end when the sliding plate moves in the closing movement direction at a lower part that is in contact with the upper surface of the lower fixing plate 7. An enlarged diameter portion 6b extending downward is provided at a position corresponding to the portion side. Further, the nozzle hole 7a of the lower fixed plate 7 has an enlarged diameter that is widened upward at a position corresponding to the moving direction side of the sliding plate 6 on the upper side that is in contact with the lower surface of the sliding plate 6. The part 7b is extended and provided.

  In addition to providing such enlarged diameter portions 6b and 7b, the upper fixing plate 5 is provided on the upper surface in contact with the lower surface of the upper fixing plate 7 of the sliding plate 6 at the nozzle hole closing position after the sliding plate 6 is moved. A gas blowing plug 9 is provided at a position facing the nozzle hole 5a.

Accordingly, the planar shapes of the enlarged diameter portions 6b and 7b provided at the lower and upper portions of the nozzle holes 6a and 7a of the sliding plate 6 and the lower fixing plate 7 are not circular but elliptical. Moreover, as shown in FIG. 2, the sizes d ₂ and d ₃ of the elliptical long-diameter portion are larger than the diameter of the enlarged portion 6b (d ₂ ) of the nozzle hole 6a, and the enlarged portion 7b (d It is important to increase the size of ₃ ).

As described above, the reason why the enlarged diameter portions 6b and 7b (d ₂ , d ₃ ) are different in size is that the sliding plate 6 is moved to discharge the packed sand and the molten steel is poured out (casting). This is to prevent residual molten steel from being generated at least in the nozzle hole 6a when the pouring operation is stopped by sliding the sliding plate 6 after starting. That is, FIG. As shown in FIG. 4, even when the nozzle hole 5a of the upper fixed plate 5 and the nozzle hole 6a of the sliding plate 6 are completely displaced and the opening degree becomes zero (ie, closed), the sliding plate 6 The nozzle hole 6a and the nozzle hole 7a of the lower fixing plate 7 are shown in FIG. FIG. 3-d. As shown in FIG. 5, the state of communication through the respective enlarged diameter portions 6b and 7b can be maintained, and no molten steel remains in the nozzle holes 6a and 7a. About molten steel, it can discharge | emit completely through this enlarged diameter part 6b, 7b.

  Another reason why the nozzle hole enlarged portion 7b of the lower fixing plate 7 is made larger than the nozzle hole enlarged portion 6b of the sliding plate 6 is that the position of the gas blowing plug 9 is Therefore, the time during which the nozzle hole 6a of the sliding plate 6 and the nozzle hole 7a of the lower plate 7 communicate with each other becomes longer, and at least residual molten steel in the nozzle hole 6a is eliminated, and the sliding nozzle is re-poured. This is because it is effective to prevent non-opening of time.

Next, a method for operating the sliding nozzle device (a method for pouring molten steel) will be described.
The basic method of pouring molten steel into the dispensing container (receptor) is to use the sliding nozzle device to pour molten metal in the molten metal holding container 2 such as tundish into the dispensing container. The nozzle hole 6a of the sliding plate 6 and the lower fixing plate are not communicated with each other between the nozzle hole 5a of the upper fixing plate 5 and the nozzle hole 6a of the sliding plate 6. In order to communicate with each other through the respective enlarged diameter portions 6b and 7b, and for a certain period of time (1 to 10 seconds, preferably about 2 to 4 seconds), By sliding or stopping the sliding plate 6, at least molten steel remaining in the nozzle hole 6a of the sliding plate 6 is discharged to the nozzle hole 7a.

Specifically, as shown in FIG.
Step a: discharging packed sand, starting casting molten steel into a pouring container such as a mold or a ladle (degree of communication of nozzle holes 5a, 6a: opening degree 100%),
Step b: Continuation of casting operation, preparation for closing (nozzle hole 5a, 6a communication degree: opening degree 50%),
Step c: is a step of promoting the discharge of molten steel in the nozzle hole 6a of the sliding plate 6 with the degree of communication and opening degree of the nozzle holes 5a, 6a being 0%. At this time, the step is provided on the upper surface of the sliding plate 6 A part of the gas blowing plug 9 is already stirring the molten steel in the nozzle hole 5a with respect to the nozzle hole 5a of the upper fixing plate 5;
Step d: The nozzle hole 6a of the sliding plate 6 and the nozzle hole 7a of the lower fixing plate 7 are in communication with each other only at the respective enlarged diameter portions 6b and 7b.
Step e: In a state where the molten steel in the nozzle hole 6a of the sliding plate 6 is almost discharged, the molten steel in the nozzle hole 7a is also being discharged.
It is.
In step e, bubbling gas is sprayed from the gas blowing plug 9 toward the molten steel in the nozzle hole 5a, preventing solidification of the molten steel in the nozzle hole 5a, and preventing re-pouring. By preventing the opening, it is possible to eliminate the need for a forced opening operation by oxygen gas blowing (oxygen cleaning).

  In a more preferred embodiment of the present invention, it is recommended to temporarily stop the movement of the sliding plate 6 in the step c (FIG. 3-c.) To promote the discharge of molten steel from the nozzle hole 6b. The pause time is preferably 2 seconds or more and 4 seconds or less. By this temporary stop, almost all of the molten steel in the nozzle hole 6a can be discharged, and in combination with the Ar gas bubbling from the gas blowing plug in synchronism with this timing, the nozzle holes 5a to 7a are clogged. Thus, re-pouring in the next process can be performed smoothly without causing non-opening.

  FIG. 4 shows the flow of the casting operation in the ingot making facility divided into a conventional example and an invention example. In addition, a comparative example (corresponding to non-opening) is also examined. The operation of each plate in the sliding nozzle device of the present invention is the same as that shown in FIG.

  In this embodiment, the sliding plate of the sliding nozzle device is driven by a hydraulic cylinder. The sliding speed was 100 mm / sec, and Ar gas bubbling from the gas blowing plug was blown at about 50 NL / min from a thin tube type plug provided on the sliding plate. The ladle, which is a molten metal holding container, has a capacity of 270 tons, [C] = 0.95 to 1.10 mass%, [Si] = 0.40 to 0.70 mass%, [Mn] = 0.90 to 1.15 mass%, [P] = 0.025 mass% or less, [S] = 0.025 mass% or less, [Cr] = 0.90 to 1.20 mass% of steel using a converter-RH Then, the steel was received in the ladle that was the pouring container. The molten steel temperature before casting was adjusted to a temperature 40-60 ° C. higher than the liquidus temperature.

  The results carried out under the above conditions are shown in Table 1 below in comparison with the conventional example and the comparative example. As shown in Table 1, when the sliding nozzle was opened for re-pouring, the natural aperture ratio in the conventional example and the comparative example was 0%, whereas the natural aperture in the example suitable for the present invention was The rate is 33% or more. In particular, when the movement stop time of the sliding plate in step c is 3 seconds or more, oxygen cleaning is not required at all, and the natural aperture ratio is 100%. Sex was confirmed.

  The present invention is a technique widely applied to operations using a sliding nozzle such as ingot making, continuous casting, pouring from a dundish.

DESCRIPTION OF SYMBOLS 1 Sliding nozzle apparatus 2 Molten metal holding container 3 Upper nozzle 4 Lower nozzle 5 Upper fixed plate 6 Sliding plate 7 Lower fixed plate 8 Drive cylinder 9 Gas blowing plug 5a-7a Nozzle hole 6b, 7b Nozzle hole diameter expansion part

Claims (2)

It is arranged under the upper nozzle in the bottom of the molten metal holding container, and consists of a combination of an upper and lower fixed plate and a sliding plate that is movably held between these plates. Is a sliding nozzle device having nozzle holes of substantially equal diameter communicating with each other in the open position,
The nozzle hole of the sliding plate is provided with a diameter- expanding portion that expands downward at a position corresponding to the rear end side when the plate moves in the closing direction at a lower portion on the side in contact with the upper surface of the lower fixed plate. On the other hand, the nozzle hole of the lower fixed plate is provided with an enlarged diameter- expanding portion at an upper portion on the side in contact with the lower surface of the sliding plate at a position corresponding to the moving direction side of the sliding plate, and
Each of the enlarged diameter portions provided on the sliding plate and the lower fixed plate has an elliptical shape having a different planar shape, and the enlarged diameter portion of the lower fixed plate is larger than the enlarged diameter portion of the sliding plate. Is also big,
A gas blowing plug is provided on the upper surface of the sliding plate in contact with the lower surface of the upper fixed plate at a position facing the nozzle hole of the upper fixed plate in the closed position after the sliding plate is moved. A sliding nozzle device for a molten metal holding container. When the molten metal in the molten metal holding container is poured into the dispensing container by using the sliding nozzle device according to claim 1, when the nozzle hole is closed at the end of the molten metal pouring,
Although in between the nozzle hole and the sliding plate of the nozzle hole of the upper fixing plate in the closed state of the nozzle holes with each other are not in communication with, between the nozzle hole of the nozzle hole and the lower fixed plate of the sliding plate, the sliding The nozzle hole of the moving plate is provided with a diameter-expanding portion that expands downward at a position corresponding to the rear end side when the plate moves in the closing direction at the lower part on the side in contact with the upper surface of the lower fixed plate, The nozzle hole of the lower fixed plate is provided with an enlarged diameter portion provided on the upper portion of the sliding plate in contact with the lower surface of the lower fixed plate, with an enlarged diameter portion extending upward at a position corresponding to the moving direction side of the sliding plate. a state of communicating only hand together rather guide, discharged by the this state Turkey to hold to move the stop 10 seconds of the sliding plate, the melt remaining in the nozzle hole of at least the sliding plate To do Molten metal pouring process from the molten metal holding vessel for the sliding nozzle device according to claim.

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