Submerged Nozzle Replacement Apparatus

The present invention relates to an immersion or submerged nozzle replacement apparatus mounted to the under side of a molten steel discharge port of a tundish.

In continuous casting of steel, molten steel is poured into a mold from a molten steel discharge port provided at the bottom of a tundish via an immersion or submerged nozzle. In such continuous casting of steel, the submerged nozzle is used under severe conditions in which an inner bore thereof is in contact with molten steel being flowing, and an outer surface thereof is in touch with outside air, so that it often receives a damage such as wear, chipping, or fracture. Thus, frequent replacement is required according to the damage.

For this purpose, a submerged nozzle replacement apparatus as disclosed in, e.g., Patent Document 1, has heretofore been used. In a normal state, such a submerged nozzle replacement apparatus is used to replace a used submerged nozzle with a new submerged nozzle. However, in order to stop the outflow of molten steel in an emergency, it can be used to replace a submerged nozzle with a closing refractory, i.e., a blank plate.

During continuous casting, the blank plate is kept in a standby position on the rear side of a submerged nozzle in use. For this reason, in the conventional submerged nozzle replacement apparatus, after replacing the used submerged nozzle with a new submerged nozzle, a worker has performed an operation of moving the blank plate to the standby position.

The movement of the blank plate to the standby position needs to be completed quickly and easily. However, the conventional submerged nozzle replacement apparatus has not been able to fulfill such a need.

Patent Document 1: JP 3232294 B2

A technical problem to be solved by the present invention is to provide a submerged nozzle replacement apparatus capable of quickly and easily moving a blank plate to a standby position.

According to one aspect of the present invention, the following submerged nozzle replacement apparatus is provided.

A submerged nozzle replacement apparatus mounted to an under side of a molten steel discharge port of a tundish, the submerged nozzle replacement apparatus comprising: a pressing section to press a lower surface of a flange portion of a submerged nozzle; an introducing section to, when attaching the submerged nozzle, guide said submerged nozzle to the pressing section; an ejecting section to, when detaching the submerged nozzle from the pressing section, guide said submerged nozzle to a detaching position; and a holding section that holds a blank plate, wherein the holding section is movable between a first position where the blank plate is opposed to the submerged nozzle in a state of being supported by the pressing section, and a second position where the lower surface of the flange portion of the submerged nozzle can be supported by the holding section and the introducing section.

The submerged nozzle replacement apparatus according to the present invention is capable of quickly and easily moving the blank plate to the standby position.

andshow a submerged nozzle replacement apparatus according to one embodiment of the present invention, in the form of a perspective view as viewed obliquely upwardly from a front and lower side thereof and a perspective view as viewed obliquely downwardly from a rear and upper side thereof, respectively.shows a relevant part of the submerged nozzle replacement apparatus in a state of being mounted to a tundish, in the form of an enlarged sectional view taken along the line A-A of. It should be noted that, as used in this specification, the terms “front side” and “rear side” are based on a moving direction of a submerged nozzle when replacing the submerged nozzle with a new one in the submerged nozzle replacement apparatus. More specifically, the “front side” refers to a front side (leading side) in the moving direction of the submerged nozzle, and the “rear side” refers to a rear side (trailing side) in the moving direction of the submerged nozzle.

As shown in, the submerged nozzle replacement apparatusis mounted to the under side of a molten steel discharge portof a tundish. Specifically, a frameof the submerged nozzle replacement apparatusis fixed to a shellat the bottom of the tundishby bolts or the like.

Referring totogether with, the submerged nozzle replacement apparatuscomprises: a pressing sectionto press a lower surface of a flange portionof a submerged nozzle; an introducing sectionto, when attaching the submerged nozzle, guide said submerged nozzle to the pressing section; an ejecting sectionto, when detaching the submerged nozzlefrom the pressing section, guiding the submerged nozzleto a detaching position; and a holding sectionto hold a blank plate. The submerged nozzle replacement apparatusalso comprises a support sectionto support a tundish nozzle. The tundish nozzlehas a flange portionand a tubular portion. The tubular portionof the tundish nozzleis inserted into the molten steel discharge portof the tundish. Further, a lower surface of the flange portionof the tundish nozzleis joined to an upper surface of the flange portionof the submerged nozzle. In this way, molten steel in the tundishis transferred to a mold via the tundish nozzleand the submerged nozzle.

As mentioned above, in a normal state, the submerged nozzle replacement apparatusis used to replace a used submerged nozzle with a new submerged nozzle. However, in order to stop the outflow of molten steel in an emergency, it can be used to replace a submerged nozzle with the blank plate. For this purpose, during continuous casting, the blank plateis kept in a standby position on the rear side of the submerged nozzlein use, as shown in. More specifically, during continuous casting, the holding sectionthat holds the blank plateis in a first position where the blank plateis opposed to the submerged nozzlein use, i.e., in a state of being supported by the pressing section.

On the other hand, when a used submerged nozzle is replaced with a new submerged nozzle, the blank plateis retracted to a retracted position where the blank platedoes not hinder the replacement between the submerged nozzles, as shown in. More specifically, when replacing a used submerged nozzle with a new submerged nozzle, the holding sectionthat holds the blank plateis moved from the first position illustrated into a second position illustrated in. Then, a new submerged nozzle′ is placed on the rear side of the used submerged nozzle, as shown in.

is a view whenis viewed in a direction of an arrowed line B in. As is clearly appearing in, the new submerged nozzle′ is placed on the rear side of the used submerged nozzle, in a state in which a lower surface of a flange portion′ of the new submerged nozzle′ is supported by the holding sectionlying in the second position and the introducing section. In this embodiment, the introducing sectionis composed of a guide rail to support one side of the lower surface of the flange portion′ of the new submerged nozzle′, and is configured to, when attaching the new submerged nozzle′, guide said new submerged nozzle′ to the pressing section, in cooperation with the holding sectionlying in the second position.

Further, in this embodiment, the pressing sectionis composed of a plurality of keyboard-shaped pressing membersto press the submerged nozzleagainst the tundish nozzle, as appearing in. More specifically, the plurality of pressing membersare configured to support the lower surface of the flange portionof the submerged nozzle. Each of the pressing membersis configured to press the submerged nozzleagainst the tundish nozzleby an elastic force of a coil springas an elastic body housed in a spring box.

Further, in this embodiment, as appearing in, the ejecting sectionis composed of a pair of guide rails capable of supporting one side and the other side of the lower surface of the flange portionof the submerged nozzle, respectively, and is configured to, when detaching the submerged nozzlefrom the pressing section, guide said submerged nozzleto the detaching position.

The submerged nozzle replacement apparatuscomprises: a pusheras a pushing tool to push the new submerged nozzle′ placed on the rear side of the used submerged nozzle, as shown in, and move the new submerged nozzle′ forwardly in the direction B in; and a hydraulic cylinderas a drive device to move the pusherforwardly in the direction B or backwardly in a direction opposite to the direction B. The hydraulic cylinderis fixed to a portion of the frameon the side of the introducing section. A base endof the pusheris connected to a rotary member configured to rotate along with forward and backward movements of a cylinder rod of the hydraulic cylinder, and is configured to be swung downwardly and upwardly along with the forward and backward movements of the cylinder rod of the hydraulic cylinder. Specifically, as shown in, when the cylinder rod of the hydraulic cylinderis in a backward limit position, the pusheris swung upwardly to a position above an upper surface of the flange portion′ of the new submerged nozzle′. Then, when the cylinder rod of the hydraulic cylinderis slightly moved forwardly, the pusheris swung downwardly to a position overlapping the flange portion′ of the new submerged nozzle′, as shown in. In this state, the cylinder rod of the hydraulic cylindercan be further moved forwardly to allow the pusherto push and move the flange portion′ of the new submerged nozzle′ forwardly in the direction B in. After completion of the above operation, when the cylinder rod of the hydraulic cylinderis returned to the backward limit position, the pusheris returned to the original position in.

As just described, when the cylinder rod of the hydraulic cylinderis in the backward limit position, the pusheris in the position illustrated in. Thus, in an operation of placing the new submerged nozzle′ on the rear side of the used submerged nozzle, the pusherdoes not hinder the operation. Then, after placing the new submerged nozzle′ on the rear side of the used submerged nozzle, the cylinder rod of the hydraulic cylinderis moved forwardly, so that the new submerged nozzle′ is moved from the introducing sectionto the pressing section, while pushing the used submerged nozzle. Accordingly, the used submerged nozzleis moved from the pressing sectionto the ejecting section. In this way, the used submerged nozzleis replaced with the new submerged nozzle′.

In this embodiment, the pusheris configured to be automatically swung downwardly and upwardly along with the forward and backward movements of the cylinder rod of the hydraulic cylinder. Alternatively, the pushermay be configured to be manually swung downwardly and upwardly by using, e.g., a hinge mechanism.

Next, the holding sectionwill be described in detail.illustrates a holding sectionand its accessory member in an exploded perspective view.

As mentioned above, the holding sectionis movable between the first position illustrated inand the second position illustrated in. Specifically, in this embodiment, the holding sectionis swung about a hinge pinas a swing center, so thar it is moved between the first position and the second position. More specifically, in this embodiment, the holding sectionhas an approximately rectangular shape in plan view, and comprises a hinge portionformed at one corner thereof. The hinge portionis gripped by a hinge gripper portionof a hinge bracket, and the hinge pinpenetrates through a through-holeof the hinge portionand a through-holeof the hinge gripper portion. Accordingly, the holding sectionis swingable about the hinge pinas a swing center.

As appearing in, the hinge bracketis attached to a rear side of the spring boxsuch that the hinge gripper portionis located adjacent to the pressing sectionillustrated in. Accordingly, the hinge pinis positioned on the rear side of and adjacent to the pressing section. That is, in this embodiment, the holding sectionis swung about the hinge pinas a swing center, which is positioned on the rear side of and adjacent to the pressing section, so that it is moved between the first position and the second position.

In this embodiment, the hinge gripper portioncomprises an upper plateand a lower platewhich is larger than the upper plateSince the lower plateis a member to support a lower surface of the holding section, enlarging the lower platemakes it possible to suppress downward bending of the holding sectionthat holds the blank plate, when said holding sectionis swung, and thus accurately move the holding sectionbetween the first position and the second position.

Further, in this embodiment, a side surface portionof the holding sectionopposed to the introducing sectionwhen the holding sectionis in the first position, and a side surface portionof the holding sectionopposed to the blank platewhen the holding sectionis in the second position, are provided with a magnetand a magnetrespectively. A heat-resistant magnet is used as each of the magnetsThe magnetwhich appears in, is opposed to the introducing sectionwhen the holding sectionis in the first position. At this time, the magnetfulfills a function of positioning the holding sectionto prevent the holding sectionfrom unexpectedly moving to the second position. The magnetwhich appears in, is opposed to the hinge bracketwhen the holding sectionis in the second position. At this time, the magnetfulfills a function of positioning the holding sectionto prevent the holding sectionfrom unexpectedly moving to the first position.

is a perspective view of the blank plateto be held by the holding sectionas viewed obliquely upwardly from a lower side of the blank plate. The blank plateis replaced with a submerged nozzle in use, i.e., the submerged nozzlein a state of being supported by the pressing section, in order to stop the outflow of molten steel in an emergency. For this purpose, the blank platehas substantially the same outer shape as that of the flange portionof the submerged nozzle.

As appearing in, a protrusionis provided on a lower surface of the blank plate. On the other hand, as appearing in, a cutouthaving an openingat one end thereof is provided in the holding sectionto hold the blank plate. The blank plateis held by the holding section, in a state in which the protrusionis inserted from the side of the one end of the cutout.

Here, the openingof the holding sectionfaces the front side, i.e., the pressing section, when the holding sectionis in the first position, as shown in. The blank plateis pushed forwardly toward the pressing sectionin an emergency. In this process, the protrusionof the blank plateis pushed out through the openingof the cutoutof the holding section. Thus, the blank platecan be moved toward the pressing section. Further, in this process, the blank plateis moved while the protrusionon the lower surface thereof is guided by the cutout. This makes it possible to smoothly move the blank platetoward the pressing section.

The length Lof the blank platein the moving direction thereof is less than the length Lof the holding section. Thus, when the holding sectionis in the second position, as illustrated in, the lower surface of the flange portion′ of the new submerged nozzle′ is supported by the holding sectionand the introducing section, as appearing in. As just described, in this embodiment, the holding sectioncomprises a first holding portionA to hold the blank plate, and a second holding portionB capable of supporting the lower surface of the flange portion′ of the new submerged nozzle′. In this embodiment, the first holding sub-sectionA and the second holding sub-sectionB lie in the same plane, and the second holding sub-sectionB is located on the front side of the first holding sub-sectionA in the moving direction of the blank plate. Since the first holding sub-sectionA and the second holding sub-sectionB lie in the same plane, and the height level of the first holding sub-sectionA and the second holding sub-sectionB is substantially the same as the height level of the pressing section, the movement of the blank platetoward the front side, i.e., toward the pressing sectionis not hindered.

On the other hand, the width Wof the blank platein a direction orthogonal to the moving direction is greater than the width Wof the holding section. Thus, when the holding sectionis in the first position, as illustrated in, a part of the lower surface of the blank plateon one side in the width direction is supported by the introducing section, as appearing inwhich is a view whenis viewed in a direction of an arrowed line B in.

With a view to preventing the blank plateheld by the first holding sub-sectionA from unexpectedly moving toward the second holding sub-sectionB, the first holding sectionA may be provided with positioning means, such as a magnet, for positioning the blank plate.

Next, the operation of the submerged nozzle replacement apparatus, in particular, the operation of the holding sectionand the blank plate, will be described.

As mentioned above, during continuous casting, the holding sectionis in the first position as shown in. Then when the used submerged nozzleis replaced with the new submerged nozzle′, the holding sectionis moved to the second position as shown in, and the new submerged nozzle′ is placed on the rear side of the used submerged nozzleas shown in. At this time, the lower surface of the flange portion′ of the new submerged nozzle′ is supported by the second holding sub-sectionB of the holding sectionlying in the second position and the introducing section, as appearing in. Subsequently, the cylinder rod of the hydraulic cylinderis moved forwardly as mentioned above, so that the new submerged nozzle′ is moved from the introducing sectionto the pressing sectionwhile pushing the used submerged nozzle. Accordingly, the used submerged nozzleis moved from the pressing sectionto the ejecting section. When the holding sectionis in the second position, the second holding sub-sectionB is positioned with respect to the pressing sectionsuch that it is continuous with the pressing section. Further, the introducing sectionis also positioned with respect to the pressing sectionsuch that it is continuous with the pressing section. This makes it possible to smoothly move the new submerged nozzle′ from the introducing sectionto the pressing sectionwhile pushing the used submerged nozzle.

In this way, the used submerged nozzleis replaced with the new submerged nozzle′. Generally, such a submerged nozzle replacement operation is performed after the continuous casting is interrupted, e.g., by fitting a well-known stopper into the tundish nozzle. However, this submerged nozzle replacement operation may be performed during continuous casting.

After completion of the submerged nozzle replacement operation, the holding sectionis moved from the second position illustrated into the first position illustrated in. As mentioned above, in this embodiment, the holding sectionis moved between the first position and the second position by being swung about the hinge pinas a swing center.shows a state in which the holding section is being moved.

In a state after moving the holding sectionto the first position, the blank plateis held by the first holding sub-sectionA of the holding sectionas appearing in, and a part of the lower surface of the blank plateon one side in the width direction is supported by the introducing section. At this time, the blank plateis opposed to the submerged nozzlein use, i.e., in a state of being supported by the pressing section, wherein a gap S is present between the flange portionof the submerged nozzlein use and the blank plate, as appearing inwhich is a bottom view of the submerged nozzle replacement apparatus in. The presence of the gap S makes it possible to reduce the possibility that the submerged nozzleand the blank plateare damaged due to collision of the blank platewith the submerged nozzlewhen the holding sectionis moved to the first position.

When stopping the outflow of molten steel in an emergency, the cylinder rod of the hydraulic cylinderis moved forwardly in the same manner as the submerged nozzle replacement operation. Thus, the blank plateis moved from the introducing sectionto the pressing sectionwhile pressing the submerged nozzlein use, i.e., in a state of being supported by the pressing section, and accordingly the submerged nozzlein use is moved from the pressing sectionto the ejecting section. As a result, the submerged nozzlein use is replaced with the blank plateas shown inso as to stop the outflow of molten steel.

The plurality of pressing membersconstituting the pressing sectionappear in. In, the blank plateis pressed against the tundish nozzleby the plurality of pressing members, in the same manner as that for the submerged nozzlein use.

As above, in this embodiment, the holding sectionis movable between the first position and the second position. Here, the first position is a standby position of the blank plate, and the second position is a retracted position of the blank plate. That is, according to this embodiment, the blank platecan be moved between the standby position and the retracted position quickly and easily by moving the holding sectionbetween the first position and the second position.

Further, in this embodiment, in a state in which the holding sectionis in the second position that is the retracted position of the blank plate, the second holding sub-sectionB of the holding sectionsupports the lower surface of the flange portion′ of the new submerged nozzle′, in cooperation with the introducing sectioncomposed of a single guide rail, and guides the submerged nozzle′ to the pressing section. In a conventional submerged nozzle replacement apparatus, a component equivalent to the introducing sectionin this embodiment is composed of a pair of guide rails (two guide rails), as disclosed in, e.g., the Patent Document. Differently, in this embodiment, since the second holding sub-sectionB of the holding sectionfunctions as a guide rail, as mentioned above, the introducing sectioncan be composed of only one guide rail. This makes it possible to achieve device compactification along with the advantage that a swing trajectory of the holding sectionbecomes smaller.

Further, the smaller swing trajectory of the holding sectionalso contributes to quick and easy movement of the blank platebetween the standby position and the retracted position.

Further, since the holding sectioncan be placed in the second position during the submerged nozzle replacement operation, device compactification can be promoted as compared to, e.g., a case where a blank plate holding section is separately provided outside the introducing section. Thus, the submerged nozzle replacement apparatus can be installed even if an installation location of the tundish has a relatively narrow space.

In the above embodiment, the movement of the holding sectionbetween the first position and the second position is performed by “swing motion”. Alternatively, it may be performed by “translational motion”. However, from a viewpoint of making it easy to avoid interference with other components constituting the submerged nozzle replacement apparatus, “swing motion” is preferable. Further, in case of “swing motion”, it is preferable that the swing center thereof is set at a position adjacent to the pressing section, from a viewpoint of making the swing trajectory of the holding sectionsmaller.

In the above embodiment, the holding sectionis positioned in the first or second position by utilizing a magnetic force of a magnet. Alternatively, a mechanical fitting-engagement force or the like may be utilized. Further, with a view to allowing the holding sectionto be accurately moved to the first position when moving the holding sectionto the first position, a taper fitting structuremay be provided in which the holding sectionand the introducing sectionare provided, respectively, with two inclined surfaces, and the holding sectionis guided to a fixed position relative to the introducing section, under contact between the two inclined surfaces, as hypothetically illustrated in.

In the above embodiment, the submerged nozzle replacement apparatusis configured to replace the submerged nozzleof a type in which it is directly joined to the tundish nozzle. Alternatively, it may be configured to replace a submerged nozzle of a type in which it is joined to a lower nozzle of a well-known sliding nozzle device which is interposed between the tundish nozzle and the submerged nozzle.