Immersion nozzle replacement apparatus and immersion nozzle

Abstract

The present invention provides an immersion nozzle replacement apparatus that can switch a movement amount of an immersion nozzle in a straight direction without switching a stroke of a linear motion drive apparatus between during nozzle replacement and during molten steel blocking and an immersion nozzle for suitable use in the immersion nozzle replacement apparatus. The immersion nozzle replacement apparatus of the present invention has a linear motion drive apparatus 8 having a fixed stroke and a pusher arm 9 bumping against an immersion nozzle 300 (300') to move the immersion nozzle in the straight direction. The pusher arm 9 can horizontally turn and can move in the straight direction when driven by the linear motion drive apparatus 8. A movement amount of the immersion nozzle 300 (300') in the straight direction can be switched between during nozzle replacement and during molten steel blocking by changing a horizontal turning angle of the pusher arm 9.

Description

IMMERSION NOZZLE REPLACEMENT APPARATUS AND IMMERSION NOZZLE

[0001] The present invention relates to an immersion nozzle replacement apparatus mounted below a molten steel outlet of a tundish and an immersion nozzle for use in the immersion nozzle replacement apparatus.

[0002] In continuous casting of steel, molten steel is injected into a mold from a molten steel outlet provided at the bottom of a tundish via an immersion nozzle. In such continuous casting of steel, the immersion nozzle is used under severe conditions in which its inner hole face of an inner hole, which serves as an injection channel for molten steel, is in contact with flowing molten steel and its outer face is in contact with the outside air, and thus damage such as melt damage, chipping, or breakage is common. As a result, the immersion nozzle requires frequent replacement in accordance with damage.

[0003] For this reason, immersion nozzle replacement apparatuses such as one disclosed in Patent Literature 1 have been conventionally used. Usually, the immersion nozzle replacement apparatus is used to replace an old immersion nozzle (an immersion nozzle in use) with a new immersion nozzle (an immersion nozzle for replacement), but in some cases the immersion nozzle in use may be replaced with a refractory for closure, or what is called a blank plate, in order to block an outflow of molten steel when operations need to stop in an emergency.

[0004] During continuous casting, the blank plate is kept waiting on the rear side of the immersion nozzle in use. Thus, operators have conventionally moved the blank plate to its waiting position after replacing the old immersion nozzle (the immersion nozzle in use) with the new immersion nozzle (the immersion nozzle for replacement). Such movement of the blank plate to the waiting position and molten steel blocking by the blank plate require quickness and simplicity, but conventional technologies have not been able to meet the requirements.

[0005] Given these circumstances, as a technology to achieve molten steel blocking without using the blank plate, Patent Literature 2, for example, develops a technology to move an upper flange part (a plate) of the immersion nozzle to a casting position or sealing position, specifically, to move it to the casting position during nozzle replacement and to move it to the sealing position during molten steel blocking. However, when nozzle replacement and molten steel blocking are thus performed by the upper flange part (the plate) of the immersion nozzle without using the blank plate, it is necessary to switch a movement amount of the immersion nozzle in a straight direction between during nozzle replacement and during molten steel blocking. Thus, in conventional technologies, it is necessary to switch the stroke of a linear motion drive apparatus such as a hydraulic cylinder by, for example, using a (three-port) hydraulic cylinder that can switch between two kinds of strokes, stopping the linear motion drive apparatus in the middle of the stroke by an electrical limit switch mechanism, or limiting the motion of a rod (12) by pivotally moving a lever (32) with a mechanical limiting mechanism as disclosed in Patent Literature 2. That is, conventional technologies require to include a mechanism to switch the stroke of the linear motion drive apparatus. Furthermore, in the case of using the mechanical limiting mechanism as disclosed in Patent Literature 2, there is also a problem in that load is applied to the components constituting the mechanical limiting mechanism (in Patent Document 2, the lever (32) and the rod (12)).

[0006] Japanese Patent No. 3232294Japanese Patent No. 5824027

[0007] An object of the present invention is to provide an immersion nozzle replacement apparatus that can switch a movement amount of an immersion nozzle in a straight direction without switching a stroke of a linear motion drive apparatus between during nozzle replacement and during molten steel blocking and an immersion nozzle for suitable use in the immersion nozzle replacement apparatus.

[0008] According to an aspect of the present invention, the following immersion nozzle replacement apparatus is provided. An immersion nozzle replacement apparatus mounted below a molten steel outlet of a tundish and including a molten steel blocking function of blocking an outflow of molten steel in addition to a nozzle replacing function of replacing an immersion nozzle, the immersion nozzle replacement apparatus including: a linear motion drive apparatus having a fixed stroke; and a pusher arm bumping against an immersion nozzle to move the immersion nozzle in a straight direction, the pusher arm being capable of horizontally turning, and capable of moving in the straight direction when driven by the linear motion drive apparatus, and a movement amount of the immersion nozzle in the straight direction being capable of being switched between during nozzle replacement and during molten steel blocking by changing a horizontal turning angle of the pusher arm.

[0009] According to another aspect of the present invention, an immersion nozzle for suitable use in the immersion nozzle replacement apparatus of the present invention is provided.

[0010] According to the immersion nozzle replacement apparatus of the present invention, the movement amount of the immersion nozzle in the straight direction can be switched between during nozzle replacement and during molten steel blocking by changing the horizontal turning angle of the pusher arm, and thus the movement amount of the immersion nozzle in the straight direction can be switched without switching the stroke of the linear motion drive apparatus. This can achieve both functions of the nozzle replacing function and the molten steel blocking function, using the linear motion drive apparatus having a fixed stroke without including a mechanism to switch the stroke of the linear motion drive apparatus. According to the immersion nozzle replacement apparatus of the present invention, the movement amount of the immersion nozzle in the straight direction can be switched between during nozzle replacement and during molten steel blocking by changing the horizontal turning angle of the pusher arm, and thus there is no need to provide a mechanical limiting mechanism or the like as described above, and the load on each component can be significantly reduced. According to the immersion nozzle of the present invention, as described below in detail, when an immersion nozzle for replacement is set in a setting part of the immersion nozzle replacement apparatus, it can be made unable to be set in a wrong orientation or the immersion nozzle for replacement set in the wrong orientation can be made unable to be moved in the straight direction.

[0011] FIG. 1 is a perspective view of an immersion nozzle replacement apparatus as an embodiment of the present invention, viewed from the lower rear side.FIG. 2 is a sectional view of the principal part of the immersion nozzle replacement apparatus in FIG. 1 mounted on a tundish (an A-A enlarged sectional view of FIG. 1).FIG. 3 is a diagram of the principal part of an immersion nozzle: (a) a plan view, (b) a front view, and (c) a left side view.FIG. 4 is a diagram of the configuration of the principal part of the immersion nozzle replacement apparatus in FIG. 1 including a linear motion drive apparatus and a pusher arm: (a) a sectional view, (b) a front view, and (C) a bottom view.FIG. 5 is a perspective view of the configuration of the pusher arm.FIG. 6 is a perspective view of the configuration of a drive member.FIG. 7A is a diagram of an initial state of the immersion nozzle replacement apparatus during nozzle replacement.FIG. 7B is a diagram of a state in which a tip of the pusher arm has just bumped against an upper flange part of an immersion nozzle for replacement by advancing the linear motion drive apparatus from the initial state in FIG. 7A to move the pusher arm in a straight direction.FIG. 7C is a diagram of a state in which the linear motion drive apparatus has been further advanced from the state in FIG. 7B.FIG. 7D is a diagram of a state in which the linear motion drive apparatus has been advanced to an advancement limit from the state in FIG. 7C.FIG. 8A is a diagram of an initial state of the immersion nozzle replacement apparatus during molten steel blocking.FIG. 8B is a diagram of a state in which the tip of the pusher arm has just bumped against an upper flange part of an immersion nozzle in use by advancing the linear motion drive apparatus from the initial state in FIG. 8A to move the pusher arm in the straight direction.FIG. 8C is a diagram of a state in which the linear motion drive apparatus has been advanced to an advancement limit from the state in FIG. 8B.FIG. 9 is a diagram of another embodiment about an interfering part and an interfered part.

[0012] FIG. 1 illustrates an immersion nozzle replacement apparatus as an embodiment of the present invention with a perspective view viewed from the lower rear side. FIG. 2 illustrates the principal part of this immersion nozzle replacement apparatus mounted on a tundish with an A-A enlarged sectional view of FIG. 1. Note that in the present specification, the "front side" and the "rear side" are based on the moving direction of an immersion nozzle when the immersion nozzle is replaced in the immersion nozzle replacement apparatus. That is, the "front side" refers to a front side in the moving direction of the immersion nozzle, and the "rear side" refers to a rear side in the moving direction of the immersion nozzle.

[0013] As illustrated in FIG. 2, this immersion nozzle replacement apparatus 1 is mounted below a molten steel outlet 201 of a tundish 200. Specifically, a frame 2 of the immersion nozzle replacement apparatus 1 is fixed to an iron shell 202 at the bottom of the tundish 200 with bolts or the like. Referring to FIG. 1 together with FIG. 2, the immersion nozzle replacement apparatus 1 has a pressing part 3 pressing the underside of an upper flange part 301 of an immersion nozzle 300 in use, a setting part 4 setting an immersion nozzle for replacement, which will be described below, and a discharge part 5 guiding the immersion nozzle 300 in use to a removal position when the immersion nozzle 300 in use is replaced with the immersion nozzle for replacement. The immersion nozzle replacement apparatus 1 also has a support part 6 supporting a tundish nozzle 400. The tundish nozzle 400 has a lower flange part 401 and a tubular part 402 and has an inner hole 403 serving as a discharge channel for molten steel. The tubular part 402 of the tundish nozzle 400 is inserted into the molten steel outlet 201 of the tundish 200. The underside of the lower flange part 401 of the tundish nozzle 400 is joined to the upper side of the upper flange part 301 of the immersion nozzle 300. With this configuration, molten steel in the tundish 200 is injected into a mold via the tundish nozzle 400 and the immersion nozzle 300.

[0014] FIG. 3 illustrates the principal part of the immersion nozzle 300. The immersion nozzle 300 has the upper flange part 301 and a tubular part 302 and has an inner hole 303 serving as an injection channel for molten steel. The outer side face and the underside of the upper flange part 301 and the upper periphery of the tubular part 302 are covered with a metal case 304. In the present embodiment, the shape of the upper flange part 301 of the immersion nozzle 300 is asymmetric with respect to the inner hole 303. Specifically, the shape of the upper flange part 301 of the immersion nozzle 300 is asymmetric between the front side and the rear side in the direction of travel with respect to an inner hole center line C perpendicular to the direction of travel of the immersion nozzle 300 (a direction B (a straight direction) in FIG. 1); more specifically, the rear side in the direction of travel is longer than the front side. Note that in the present embodiment, the immersion nozzle in use and the immersion nozzle for replacement have the same configuration, but in the present specification, for convenience of description, for the symbol representing the component of the latter, a dash (') is attached to the symbol representing the component of the former to distinguish the two from each other.

[0015] Referring again to FIG. 1 and FIG. 2 together with FIG. 3, in the present embodiment, the setting part 4 is a pair of guide rails that can support the underside of an upper flange part 301' of an immersion nozzle 300' for replacement and guides the set immersion nozzle 300' for replacement to the pressing part 3. In the present embodiment, the pressing part 3 is formed by a plurality of keyboard-shaped pressing members 31 in order to press the immersion nozzle 300 in use against the tundish nozzle 400 as represented in FIG. 2. That is, the pressing members 31 support the underside of the upper flange part 301 of the immersion nozzle 300. The pressing members 31 press the immersion nozzle 300 against the tundish nozzle 400 due to elastic force by a coil spring 71 as an elastic body housed in a spring box 7. In the present embodiment, the discharge part 5 is a pair of guide rails that can support the underside of the upper flange part 301 of the immersion nozzle 300 and guides this immersion nozzle 300 to the removal position when the immersion nozzle 300 is removed from the pressing part 3.

[0016] As represented in FIG. 1, the immersion nozzle replacement apparatus 1 has a linear motion drive apparatus 8 and a pusher arm 9. The linear motion drive apparatus 8 has a fixed stroke, and in the present embodiment, a hydraulic cylinder having a fixed stroke is used. The pusher arm 9 bumps against the immersion nozzle 300 in use or the immersion nozzle 300' for replacement set on the rear side of the immersion nozzle 300 to move the immersion nozzle 300 (300') in the straight direction (the direction B in FIG. 1). As described in detail below, the pusher arm 9 can horizontally turn, and can move in the straight direction (the direction B in FIG. 1) when driven by the hydraulic cylinder 8.

[0017] Next, a mechanism to operate the pusher arm 9 will be described. FIG. 4 illustrates the configuration of the principal part of the immersion nozzle replacement apparatus 1 including the hydraulic cylinder 8 and the pusher arm 9. In FIG. 4, (a) is a sectional view, (b) is a front view, and (c) is a bottom view, all of which illustrate the initial state of the immersion nozzle replacement apparatus 1, that is, a state in which the hydraulic cylinder 8 is at a retreat limit. Note that FIG. 4(c) omits the hydraulic cylinder 8 and part of the main body of a guide member 11, which will be described below. As illustrated in FIG. 4, the pusher arm 9 is incorporated into a drive member 10, and furthermore, the drive member 10 is incorporated into the guide member 11.

[0018] FIG. 5 and FIG. 6 illustrate the pusher arm 9 and the drive member 10 by themselves, respectively. The drive member 10 has a substantially columnar shape, has inside an arm insertion part 101 into which a basal end 91 of the pusher arm 9 can be inserted, and has a shaft 102 to be inserted into a shaft hole 911 formed in the basal end 91 of the pusher arm 9. In the present embodiment, the arm insertion part 101 is formed as a slit part in the longitudinal central part of the drive member 10. The basal end 91 of the pusher arm 9 is formed with a thick-walled part 912 having a large thickness, and the arm insertion part 101 is formed with a wide part 1011 corresponding to the thick-walled part 912. Note that the thickness of a tip 92 of the pusher arm 9 is substantially the same as the thickness of the basal end 91 excluding the thick-walled part 912. In the present embodiment, the tip 92 of the pusher arm 9 has a first tip face 921 and a second tip face 921. In this configuration, the pusher arm 9 is incorporated into the drive member 10 by inserting its basal end 91 into the arm insertion part 101 and then inserting the shaft 102 into the shaft hole 911. The pusher arm 9 incorporated into the drive member 10 can horizontally turn about the shaft 102.

[0019] Referring now to FIG. 4(a), the front end of a cylinder rod 81 of the hydraulic cylinder 8 is connected to the rear end of the drive member 10, and furthermore, an elastic body 12 is interposed between the front end of the cylinder rod 81 of the hydraulic cylinder 8 and the rear end of the basal end 91 of the pusher arm 9. In the present embodiment, the elastic body 12 is a compression coil spring, which is provided to exert elastic force horizontally turning the pusher arm 9 clockwise. This elastic force by the compression coil spring 12 positions the pusher arm 9 to an attitude with the first tip face 921 of the tip 92 protruding in a direction orthogonal to the straight direction (the direction B) in the initial state (the state in which the hydraulic cylinder 8 is at the retreat limit) illustrated in FIG. 4.

[0020] The guide member 11, on the other hand, has an inner hole 111 into which the drive member 10 can be inserted as represented in FIG. 4(a). The inner hole 111 is formed to extend in the straight direction (the direction B). The guide member 11 is provided with a guide pin 113 in a fixed manner fitting into a guide groove 103 formed at the bottom of the drive member 10 as represented in FIG. 4(c). Note that, as described above, FIG. 4(c) omits the hydraulic cylinder 8 and part of the main body of the guide member 11. As represented in FIG. 4(c) and FIG. 6, the guide groove 103 includes a straight part 103a extending in the straight direction (the direction B) and a bent part 103b bending from the front end of the straight part 103a. In the initial state (the state in which the hydraulic cylinder 8 is at the retreat limit) illustrated in FIG. 4(c), the guide pin 113 is positioned at the bent part 103b of the guide groove 103. When the cylinder rod 81 of the hydraulic cylinder 8 is advanced from this initial state, the guide groove 103 of the drive member 10 passes through the guide pin 113 fixed to the guide member 11, during which the position of the guide pin 113 is displaced to the straight part 103a from the bent part 103b. In the process in which the position of the guide pin 113 is thus displaced to the straight part 103a from the bent part 103b, the drive member 10 moves in the straight direction (the direction B) while rotating in the circumferential direction (a direction D in FIG. 4(c)) of the inner hole 111 of the guide member 11. Subsequently, when the cylinder rod 81 of the hydraulic cylinder 8 is further advanced, the drive member 10 moves in the straight direction (the direction B) while being guided by the guide pin 113 fit into the straight part 103a. Thus, the drive member 10 can move in the longitudinal direction of the inner hole 111 of the guide member 11, that is, the straight direction (the direction B) while being guided by the guide pin 113 and can also rotate in the circumferential direction (the direction D) of the inner hole 111.

[0021] As represented in FIG. 4(b), the guide member 11 has a slit part 112 leading to the inner hole 111. The slit part 112 has a first slit 112a, a second slit 112b, and a third slit 112c from the rear side and is formed in the straight direction (the direction B) as a whole. Among them, the first slit 112a and the third slit 112c have a slit width through which the basal end 91 excluding the thick-walled part 912 and the tip 92 of the pusher arm 9 can pass, but the thick-walled part 912 cannot pass. On the other hand, the second slit 112b has a slit width through which the thick-walled part 912 of the pusher arm 9 can pass.

[0022] Next, the functions of the immersion nozzle replacement apparatus 1 having the above configuration will be described. First, a nozzle replacing function that replaces the immersion nozzle will be described. FIG. 7A illustrates the initial state (the state in which the hydraulic cylinder 8 is at the retreat limit) of the immersion nozzle replacement apparatus 1 together with a positional relation with the immersion nozzle 300 in use and the immersion nozzle 300' for replacement. In FIG. 7A, the upper row is a front view and the lower row is a sectional view, and the immersion nozzle 300 in use and the immersion nozzle 300' for replacement are illustrated together with this sectional view. Such drawing notation is the same in FIGS. 7B to D and FIGS. 8A to C, which will be described below.

[0023] In the present embodiment, as described above, the immersion nozzle 300 in use and the immersion nozzle 300' for replacement are asymmetric in the planar shape of the upper flange parts 301 and 301' with respect to the inner holes 303 and 303'. Thus, when the immersion nozzle 300' for replacement is set in the setting part 4, it needs to be set with its orientation being a correct orientation. The correct orientation in the present embodiment is an orientation causing the inner hole 303' to be at a position biased toward the front side as illustrated in FIG. 7A. By setting the immersion nozzle 300' for replacement in the setting part 4 in this correct orientation, when the immersion nozzle 300' comes to a position in use, the inner hole 303 of the immersion nozzle 300 is positioned at a casting position E that is aligned with the inner hole 403 of the tundish nozzle 400. On the other hand, when the immersion nozzle 300' for replacement is set in the setting part 4, if it is set with its orientation being a wrong orientation (in the present embodiment, an orientation causing the inner hole 303' to be at a position biased toward the rear side), when the immersion nozzle 300' comes to the position in use, the inner hole 303 of the immersion nozzle 300 will be positioned at a position deviating from the casting position E, which will interfere with casting.

[0024] Given these circumstances, in the present embodiment, an interfering block 41 is provided in the setting part 4 as an interfering part as represented in FIG. 1 so that the immersion nozzle 300' for replacement cannot be set in the wrong orientation when it is set. As illustrated in FIG. 3, the immersion nozzle 300 (300') is provided with an interfered block 305 (305') as an interfered part interfering with the interfering block 41 when set in the setting part 4 in the wrong orientation in the metal case 304 below the upper flange part 301 (301'). That is, if the immersion nozzle 300' for replacement is attempted to be set in the wrong orientation, the interfered block 305' of the immersion nozzle 300' interferes with the interfering block 41 provided in the setting part 4, and thus it cannot be set in the wrong orientation.

[0025] Referring again to FIG. 7A, as described above, the figure illustrates the initial state of the immersion nozzle replacement apparatus 1, which is common to FIG. 4 in this respect. That is, the upper row of FIG. 7A (the front view) is the same as FIG. 4(b), and the lower row of FIG. 7A (the sectional view) is the same as FIG. 4(a). In the initial state of the immersion nozzle replacement apparatus 1, the pusher arm 9 is also in its initial position, and in this initial position, the pusher arm 9 rotates in a direction in which its tip 92 jumps upward as illustrated in the lower row of FIG. 7A and FIG. 4(a). This is because, as illustrated in FIG. 4(c), in the initial state of the immersion nozzle replacement apparatus 1, the guide pin 113 is positioned at the bent part 103b of the guide groove 103. That is, in the present embodiment, the positional relation between the guide pin 113 and the guide groove 103 is set such that the tip 92 of the pusher arm 9 is in a horizontal state when the guide pin 113 is positioned at the straight part 103a of the guide groove 103 and such that the tip 92 of the pusher arm 9 jumps upward when the guide pin 113 is positioned at the bent part 103b of the guide groove 103. Thus, in the initial state of the immersion nozzle replacement apparatus 1, the tip 92 of the pusher arm 9 jumps upward, and thereby the work of setting the immersion nozzle 300' for replacement in the setting part 4 can be easily performed. Note that in the initial state of the immersion nozzle replacement apparatus 1 (the state in FIG. 7A), the thick-walled part 912 of the pusher arm 9 is positioned at a position facing the first slit 112a, which has a slit width through which this thick-walled part 912 cannot pass. That is, in the initial state of the immersion nozzle replacement apparatus 1 (the state in FIG. 7A), the thick-walled part 912 of the pusher arm 9 is housed in the inner hole 111 of the guide member 11, and thereby the pusher arm 9 jumps up in a correct attitude (not horizontally turned).

[0026] FIG. 7B illustrates a state in which the first tip face 921 of the tip 92 of the pusher arm 9 has just bumped against the upper flange part 301' of the immersion nozzle 300' for replacement by advancing the hydraulic cylinder 8 from the initial state of the immersion nozzle replacement apparatus 1 (the state in FIG. 7A) to move the pusher arm 9 in the straight direction. In this state in FIG. 7B, the thick-walled part 912 of the pusher arm 9 is positioned at a position facing the second slit 112b, which has a slit width through which this thick-walled part 912 can pass. Note that in this state in FIG. 7B, the guide pin 113, which is not illustrated, is positioned at the straight part 103a of the guide groove 103, and thus the tip 92 of the pusher arm 9 is in a horizontal state.

[0027] FIG. 7C illustrates a state in which the hydraulic cylinder 8 has been further advanced from the state in FIG. 7B. Thus, when the hydraulic cylinder 8 is further advanced from the state in FIG. 7B, the tip 92 of the pusher arm 9 receives reaction force from the immersion nozzle 300' for replacement, and thereby the pusher arm 9 horizontally turns counterclockwise. Note that in the present embodiment, as described above, the elastic force horizontally turning the pusher arm 9 clockwise is exerted on the pusher arm 9 by the compression coil spring 12, but the immersion nozzle 300' has high resistance to move (slide) from the setting part 4 to the pressing part 3, and thus the reaction force exceeds the elastic force. In the states in FIG. 7B and FIG. 7C, the thick-walled part 912 of the pusher arm 9 is positioned at a position facing the second slit 112b, which has a slit width through which this thick-walled part 912 can pass, and thus the thick-walled part 912 of the pusher arm 9 does not interfere with the horizontal turning. Thus, when the hydraulic cylinder 8 is further advanced from the state in FIG. 7B, the pusher arm 9 horizontally turns counterclockwise as illustrated in FIG. 7C. At this time, the thick-walled part 912 of the pusher arm 9 passes through the second slit 112b to protrude outside the guide member 11. However, there is an upper limit to the counterclockwise horizontal turning angle of the pusher arm 9. That is, when the horizontal turning angle of the pusher arm 9 in the initial state illustrated in FIG. 7A is set as a reference (for example, 0 degree), there is an upper limit to the horizontal turning angle counterclockwise from the reference horizontal turning angle. This upper limit is defined by a first contacting face 93 (refer to FIG. 5) of the pusher arm 9 contacting a contacted face 104 of the drive member 10. On the other hand, the reference horizontal turning angle in the initial state illustrated in FIG. 7A is defined by a second contacting face 94 (refer to FIG. 5) of the pusher arm 9 contacting the inner hole face of the inner hole 111 of the guide member 11. At this reference horizontal turning angle, as described above, the pusher arm 9 is in an attitude in which the first tip face 921 of its tip 92 protrudes in a direction orthogonal to the straight direction (the direction B).

[0028] Here, the state in FIG. 7C is a state in which the counterclockwise horizontal turning angle of the pusher arm 9 has just reached the upper limit described above and a state in which a second tip face 922 of the tip 92 of the pusher arm 9 has just bumped against the upper flange part 301' of the immersion nozzle 300' for replacement. On the other hand, the state in FIG. 7B described earlier is a state in which the first tip face 921 of the tip 92 of the pusher arm 9 has just bumped against the upper flange part 301' of the immersion nozzle 300' for replacement and a state in which the horizontal turning angle of the pusher arm 9 remains at the reference horizontal turning angle described above. Thus, even if the hydraulic cylinder 8 is advanced to the state in FIG. 7C from the state in FIG. 7B, the advancement is offset by the horizontal turning of the pusher arm 9, resulting in a stroke loss in the movement stroke of the pusher arm 9 in the straight direction. Thus, during the period from the state in FIG. 7B to the state in FIG. 7C, the immersion nozzle 300' for replacement does not substantially move in the straight direction.

[0029] FIG. 7D illustrates a state in which the hydraulic cylinder 8 has been advanced to an advancement limit from the state in FIG. 7C. As described above, the state in FIG. 7C is a state in which the counterclockwise horizontal turning angle of the pusher arm 9 has just reached the upper limit, and thus when the hydraulic cylinder 8 is further advanced from this state in FIG. 7C, the advancement is directly connected to the movement of the immersion nozzle 300' for replacement in the straight direction without being offset by the horizontal turning of the pusher arm 9. The present embodiment, as illustrated in FIG. 7D, sets such that when the hydraulic cylinder 8 is advanced to the advancement limit with the immersion nozzle 300' for replacement set, the inner hole 303' of the immersion nozzle 300' for replacement is positioned at the casting position E. That is, by appropriately setting the upper limit of the counterclockwise horizontal turning angle of the pusher arm 9 in accordance with the fixed stroke of the hydraulic cylinder 8, the inner hole 303' of the immersion nozzle 300' for replacement is positioned at the casting position E when the hydraulic cylinder 8 is advanced to the advancement limit. Thus, according to the present embodiment, by using the hydraulic cylinder 8 having a fixed stroke and advancing the hydraulic cylinder 8 from the retreat limit to the advancement limit in accordance with the fixed stroke, the nozzle replacing function, which replaces the immersion nozzle 300 in use with the immersion nozzle 300' for replacement, can be achieved.

[0030] Next, a molten steel blocking function that blocks an outflow of molten steel will be described. FIG. 8A illustrates the initial state of the immersion nozzle replacement apparatus 1 together with a positional relation with the immersion nozzle 300 in use. Note that this state in FIG. 8A is the same as the state in FIG. 7A illustrated earlier except that the immersion nozzle for replacement is not set in the setting part 4. That is, since molten steel blocking is performed when operations are desired to be stopped in an emergency, it is usually performed without the immersion nozzle for replacement set in the setting part 4.

[0031] FIG. 8B illustrates a state in which the first tip face 921 of the tip 92 of the pusher arm 9 has just bumped against the upper flange part 301 of the immersion nozzle 300 in use by advancing the hydraulic cylinder 8 from the initial state of the immersion nozzle replacement apparatus 1 (the state in FIG. 8A) to move the pusher arm 9 in the straight direction. In this state in FIG. 8B, the thick-walled part 912 of the pusher arm 9 is positioned at a position facing the third slit 112c, which has a slit width through which this thick-walled part 912 cannot pass.

[0032] FIG. 8C illustrates a state in which the hydraulic cylinder 8 has been advanced to an advancement limit from the state in FIG. 8B. As described above, in the state in FIG. 8B, the thick-walled part 912 of the pusher arm 9 is positioned at a position facing the third slit 112c, which has a slit width through which this thick-walled part 912 cannot pass, and thus even if the hydraulic cylinder 8 is further advanced from this state in FIG. 8B, the pusher arm 9 will not horizontally turn. Thus, when the hydraulic cylinder 8 is further advanced from the state in FIG. 8B, the advancement is directly connected to the movement of the immersion nozzle 300 in use in the straight direction without being offset by the horizontal turning of the pusher arm 9. The present embodiment, as illustrated in FIG. 8C, sets such that when the hydraulic cylinder 8 is advanced to the advancement limit without the immersion nozzle 300' for replacement set, a flat part on the rear side of the inner hole 303 out of the upper flange part 301 of the immersion nozzle 300 in use is positioned at a molten steel blocking position F that blocks an outflow of molten steel from the inner hole 403 of the tundish nozzle 400.

[0033] As described above, according to the present embodiment, by using the hydraulic cylinder 8 having a fixed stroke and advancing the hydraulic cylinder 8 to the advancement limit from the retreat limit in accordance with the fixed stroke, the molten steel blocking function can be achieved in addition to the nozzle replacing function described above. That is, according to the present embodiment, by changing the horizontal turning angle of the pusher arm 9, the movement amount of the immersion nozzle 300 (300') in the straight direction can be switched between during nozzle replacement and during molten steel blocking. Specifically, the present embodiment is configured such that the horizontal turning angle of the pusher arm 9 is set to the angle illustrated in FIG. 7C and FIG. 7D (the upper limit horizontal turning angle described above) during nozzle replacement and is set to the angle illustrated in FIGS. 8A to 8C (the reference horizontal turning angle described above) during molten steel blocking, thereby making the movement amount of the immersion nozzle 300 (300') in the straight direction during nozzle replacement smaller than the movement amount of the immersion nozzle 300 (300') in the straight direction during molten steel blocking. In other words, in the present embodiment, the movement amount of the immersion nozzle 300 (300') in the straight direction can be switched between during nozzle replacement and during molten steel blocking by such a configuration, and thereby both functions, or the nozzle replacing function and the molten steel blocking function, can be achieved using the linear motion drive apparatus having a fixed stroke without including a mechanism to switch the stroke of the linear motion drive apparatus. Note that in the present embodiment, the horizontal turning angle of the pusher arm 9 changes according to a change in a position in the straight direction at which the pusher arm 9 contacts the immersion nozzle 300 (300') depending on whether the immersion nozzle 300' for replacement is set. That is, during nozzle replacement, the immersion nozzle 300' for replacement is set, and the pusher arm 9 contacts the immersion nozzle 300' for replacement. On the other hand, during molten steel blocking, the immersion nozzle 300' for replacement is not set, and thus the pusher arm 9 contacts the immersion nozzle 300 in use. In other words, the position in the straight direction at which the pusher arm 9 contacts the immersion nozzle 300' during nozzle replacement is on the rear side of the position in the straight direction at which the pusher arm 9 contacts the immersion nozzle 300 during molten steel blocking.

[0034] Next, another embodiment about the interfering part and the interfered part described above will be described. In the embodiment illustrated in FIG. 9, out of a pair of guide rails 4a and 4b constituting the setting part 4, the height of a rising part 4aa of one guide rail 4a is made higher than that of a rising part 4bb of the other guide rail 4b, and this is the interfering part. The metal case 304 (304') covering the outer side face of the upper flange part 301 (301') of the immersion nozzle 300 (300') is provided with an interfered block 306 (306'), and this is the interfered part. That is, if the immersion nozzle 300' for replacement is attempted to be set in the wrong orientation, the interfered block 306' of the immersion nozzle 300' interferes with the rising part 4aa of one guide rail 4a, and thus it cannot be set in the wrong orientation. In the embodiments illustrated in FIG. 1 and FIG. 9, the interfering part (the interfering block 41 and the rising part 4aa) is provided on the rear side of the setting part 4, so that the immersion nozzle 300' for replacement cannot be set in the wrong orientation when it is set in the setting part 4, but the interfering part (the interfering block 41 and the rising part 4aa) can be provided on the front side of the setting part 4, so that the immersion nozzle 300' for replacement set in the wrong orientation cannot be moved (advanced) in the straight direction.

[0035] 1 IMMERSION NOZZLE REPLACEMENT APPARATUS 2 FRAME 3 PRESSING PART 31 PRESSING MEMBER 4 SETTING PART 4a, 4b GUIDE RAIL 4aa, 4bb RISING PART 41 INTERFERING BLOCK (INTERFERING PART) 5 DISCHARGE PART 6 SUPPORT PART 7 SPRING BOX 71 COIL SPRING (ELASTIC BODY) 8 LINEAR MOTION DRIVE APPARATUS (HYDRAULIC CYLINDER) 81 CYLINDER ROD 9 PUSHER ARM 91 BASAL END 911 SHAFT HOLE 912 THICK-WALLED PART 92 TIP 921 FIRST TIP FACE 922 SECOND TIP FACE 93 FIRST CONTACTING FACE 94 SECOND CONTACTING FACE 10 DRIVE MEMBER 101 ARM INSERTION PART 1011 WIDE PART 102 SHAFT 103 GUIDE GROOVE 103a STRAIGHT PART 103b BENT PART 104 CONTACTED FACE 11 GUIDE MEMBER 111 INNER HOLE 112 SLIT PART 112a FIRST SLIT 112b SECOND SLIT 112c THIRD SLIT 113 GUIDE PIN 12 ELASTIC BODY 200 TUNDISH 201 MOLTEN STEEL OUTLET 202 IRON SHELL (BOTTOM OF TUNDISH) 300 IMMERSION NOZZLE (IMMERSION NOZZLE IN USE) 300' IMMERSION NOZZLE (IMMERSION NOZZLE FOR REPLACEMENT) 301, 301' UPPER FLANGE PART 302, 302' TUBULAR PART 303, 303' INNER HOLE (INJECTION CHANNEL FOR MOLTEN STEEL) 304, 304' METAL CASE 305, 305', 306, 306' INTERFERED BLOCK (INTERFERED PART) 400 TUNDISH NOZZLE 401 LOWER FLANGE PART 402 TUBULAR PART 403 INNER HOLE (DISCHARGE CHANNEL FOR MOLTEN STEEL) E CASTING POSITION F MOLTEN STEEL BLOCKING POSITION

Claims

1. An immersion nozzle replacement apparatus mounted below a molten steel outlet of a tundish and including a molten steel blocking function of blocking an outflow of molten steel in addition to a nozzle replacing function of replacing an immersion nozzle, the immersion nozzle replacement apparatus including: a linear motion drive apparatus having a fixed stroke; and a pusher arm bumping against an immersion nozzle to move the immersion nozzle in a straight direction, the pusher arm being capable of horizontally turning, and capable of moving in the straight direction when driven by the linear motion drive apparatus, and a movement amount of the immersion nozzle in the straight direction being capable of being switched between during nozzle replacement and during molten steel blocking by changing a horizontal turning angle of the pusher arm.

2. The immersion nozzle replacement apparatus according to claim 1, wherein the horizontal turning angle of the pusher arm changes according to a change in a position in the straight direction at which the pusher arm contacts the immersion nozzle depending on whether an immersion nozzle for replacement is set.

3. The immersion nozzle replacement apparatus according to claim 1 or 2, wherein an interfering part is provided in a setting part of an immersion nozzle for replacement in order to make the immersion nozzle for replacement unable to be set in a wrong orientation when the immersion nozzle for replacement is set or in order to make the immersion nozzle for replacement set in the wrong orientation unable to be moved in the straight direction.

4. An immersion nozzle for use in the immersion nozzle replacement apparatus according to claim 3, wherein a planar shape of an upper flange part is asymmetric with respect to an injection channel for molten steel, and the immersion nozzle has an interfered part interfering with the interfering part when being set in the setting part in the wrong orientation or when being set in the setting part in the wrong orientation and moved in the straight direction.

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