Slide gate

Information

  • Patent Grant
  • 6276573
  • Patent Number
    6,276,573
  • Date Filed
    Monday, November 13, 2000
    24 years ago
  • Date Issued
    Tuesday, August 21, 2001
    23 years ago
Abstract
A slide gate includes a frame fixed to a bottom of a molten-steel vessel, a guide frame attached to a bottom of the frame which can opened and closed, a plurality of refractory plates, a pair of surface-pressure bars and a cylinder. The plurality of refractory plates are disposed in a space surrounded by the frame and the guide frame with one of the refractory plates being slidable to control an amount of opening of a nozzle gate. The cylinder drives the slidable refractory plate to move a slide block with a protrusion. The protrusion moves a connecting member of the pair of surface-pressure bars so that the guide frame is connected with the frame and the slidable refractory plate is pressed to an immediate upper refractory plate by coil spring.
Description




FIELD OF THE INVENTION




The present invention relates to a slide gate to be mounted to the bottom of a molten-steel vessel such as a ladle or a tundish for pouring molten steel into the mold of a continuous casting device.




BACKGROUND OF THE INVENTION




It is generally known to fit the outlet of a molten-steel vessel with a slide gate and control the flow rate.




A slide gate consists mainly of a pair of refractory plates, which constitute a gate, and a mechanism to support and drive the refractory plates. One plate is moved to adjust the opening degree of the gate in order to control the flow rate of molten steel. It is necessary to effect the surface pressure between the refractory plates to prevent the static pressure of molten steel from causing the leak of molten steel from between the refractory plates. If the surface pressure is inadequate and molten steel leaks, it may lead to a serious accident.




The surface pressure between the refractory plates of an ordinary slide gates is several tenths of 1 MPa and, hence, the whole surface pressure is 2 to 10 tonf. On the other hand, because the refractories of the refractory plates are exposed to hot molten steel, they wear out rapidly. Accordingly, refractories are changed every several hours of casting. Changing refractories is troublesome: the surface pressure has to be lifted, the refractory plates have to be opened, the machine bolts and the cotters have to be removed to remove the refractories, new refractories have to be installed with the machine bolts and the cotters, and the surface pressure has to be effected again. If the surface pressure is too low, molten steel leaks from between the refractory plates. If the surface pressure is too high, the slide gate does not work due to too large sliding resistance and molten steel in the vessel cannot be poured in the mold. Therefore, it is very important to effect proper surface pressure between the refractory plates.




Accordingly, various surface-pressure application devices have been developed so far, for example, to prevent human errors or to prevent the difference in workmanship among individual workers from affecting the surface pressure. Representative devices are one to press coil springs with a linkage (Japanese Examined Utility Model publication No. 17497/S59 (1984)), one to press coil springs with bolts (Japanese Unexamined Patent publication No. 132432/S54 (1979)), and one to effect surface pressure with an actuator (Japanese Unexamined Patent publication No. 115965/H5 (1993) or 169213/H5 (1993)).




The above devices of the prior art are useful in their own ways, but not necessarily satisfactory.




In case of the device of the Japanese Examined Utility Model publication No. 17497/S59 (1984), the surface pressure can be effected just by turning a lever and, hence, the work can be made in a very short time. However, when it is adopted for a large-size slide gate which requires a surface pressure as large as several to ten odd tonf, the turning torque of the lever becomes as high as several hundred Nm. If the lever is short, a single worker cannot turn it. If it is long enough for a single worker to turn it, a large space has to be secured around it. Besides, when the surface pressure is lifted, the energy accumulated in the coil springs is released at a stroke, causing a large shock, which is unpleasant to the worker and can be dangerous.




In case of the device of the Japanese Unexamined Patent publication No. 132432/S54 (1979), by using power tools, the working time and the working space required can be reduced and labor can be saved. However, power tools are costly, they require a power source, and their noise affects the working environment. If a power source is not available, the bolts can be loosened and tightened with spanners, which however takes a long time.




In case of the devices of the Japanese Unexamined Patent publication Nos. 115965/H5 (1993) and 169213/H5 (1993), the surface pressure can be effected and lifted just by operating a valve for switching the actuator. Therefore, the pressure-effecting and lifting work itself is simple and can be made in a very short time. Besides, the valve operation can be automatized. However, since such an actuator and a valve, and a power unit for the actuator are necessary, the whole device becomes costly.




If cotters are used for installing refractories, some of them may loosen while the slide gate is in service. Machine bolts do not get loose, but threads may seize up, posing a problem to the change of refractories.




SUMMARY OF THE INVENTION




According to the first aspect of the present invention, there is provided a slide gate comprising a frame fixed to the bottom of a molten-steel vessel, a guide frame attached to the bottom of the frame so as to be openable and closable, and a plurality of refractory plates in the space surrounded by the frame and the guide frame. One of the refractory plates is slidable to control the opening degree of a nozzle gate. The frame has, on each side, a spring receiver extending in the sliding direction of said slidable refractory plate. A spring case, in which coil springs are set, is mounted on each spring receiver. Each spring case has, at each end, a pair of roller arms which extend to below the spring receiver and support a roller. A pair of surface-pressure bars is so provided that, when said guide frame is closed, each surface-pressure bar takes a position facing a spring case across the spring receiver and is movable under the guidance by the guide frame. A cylinder for driving the slidable refractory plate is utilized to move a slide block with a protrusion, and the protrusion moves a connecting member of the pair of surface-pressure bars so that the guide frame is connected with the frame and also the slidable refractory plate is pressed to the immediately upper refractory plate by the coil springs.




According to the second aspect of the present invention, there is provided a slide gate wherein each refractory plate is mounted and removed by using a wedge mechanism with a tapered member and a bolt and turning the bolt.











BRIEF DESCRIPTION OF THE DRAWINGS




The features and advantages of the present invention will become more clearly appreciated from the following description in conjunction with the accompanying drawings, in which:





FIG. 1

is a longitudinal sectional view of a slide gate of the present invention;





FIG. 2

is a sectional view taken along the line II of

FIG. 1

;





FIG. 3

is a bottom view taken along the arrowed line III—III of

FIG. 1

, the surface pressure being effected;





FIG. 4

is a side view taken along the arrowed line IV—IV of

FIG. 3

;





FIG. 5

is a side view of a surface-pressure bar


31


and a spring case


26


of

FIG. 4

;




FIGS.


6


(A) and


6


(B) are a plan view and a side view, respectively, of the guide frame


21


of

FIG. 3

;





FIG. 7

is a bottom view taken along the arrowed line III—III of

FIG. 1

, the surface pressure being lifted;





FIG. 8

is a sectional view of the slide gate of

FIG. 1

to explain the method of lifting the surface pressure;





FIG. 9

is a sectional view of the slide gate of

FIG. 1

to explain the method of effecting the surface pressure;





FIG. 10

is a plan view of a wedge mechanism of the present invention;





FIG. 11

is a sectional view taken along the arrowed line XI—XI of

FIG. 10

; and





FIG. 12

is a sectional view of another wedge mechanism of the present invention.











DETAILED DESCRIPTION OF THE INVENTION




Referring now to the drawings, a preferred embodiment of the present invention will be described.

FIGS. 1

to


7


show a slide gate


1


constructed in accordance with the present invention. The slide gate


1


has a frame


5


which is fixed to the bottom of a molten-steel vessel


2


by supports


4


and bolts


3


. The frame


5


has a recess


7


to receive an upper plate


6


. Fixed to one end of the frame


5


is a cylinder


10


which drives a moving frame


8


through a slide block


9


. The cylinder


10


has a cylinder rod


11


, which has a T-shaped head


12


at its outer end. The slide block


9


has a T-shaped groove


13


, which engages the T-shaped head


12


by receiving it within. Thus, the slide block


9


is connected to the cylinder


10


. On the other hand, a T-shaped coupler head


14


is provided on a side of the slide block


9


, said side facing the moving frame


8


. The moving frame


8


has a T-shaped groove


15


, which engages the T-shaped coupler head


14


by receiving it within. Thus, the moving frame


8


is connected to the slide block


9


, and hence the moving frame


8


is connected to the cylinder


10


through the slide block


9


. The cylinder


10


reciprocates the slide block


9


along guide grooves formed by the frame


5


and guide plates


16


.




A recess


18


is formed in the top of the moving frame


8


to receive a slide plate


17


, and a lower-nozzle holder


20


is provided at the bottom of the moving frame


8


to hold a lower nozzle


19


.




A guide frame


21


is attached to the frame


5


by pins


22


so that it can be opened and closed by turning it about the pins


22


, and the guide frame


21


and the moving frame


8


are so configured that they can be opened and closed as a unit by turning them about the pins


22


. Sliding-surfaces are formed on the top of the guide frame


21


, and the moving frame


8


is placed on the sliding-surfaces so as to be slidable. The numeral


23


indicates moving-frame guides provided on the guide frame


21


and protruding toward the moving frame


8


, and the numeral


24


is an upper nozzle.




Now a surface-pressure application device will be described.




The surface-pressure application device consists of two units. One unit is mounted on one side of the frame


5


; the other unit, on the other side. The frame


5


has a spring receiver


5




a


on each side. A spring case


26


, wherein coil springs


25


are set, is mounted on each spring receiver


5




a


by means of pre-loading bolts


27


. As shown in

FIG. 5

, each spring case


26


is provided at one end with a pair of roller arms


29




a


supporting a roller


28




a


and at the other end with a pair of roller arms


29




b


supporting a roller


28




b.






A roller


30




a


and a roller


30




b


are provided on each side of the guide frame


21


as shown in

FIG. 6

, and provided on each side of the guide frame


21


is a surface-pressure bar


31


, in the shape a hook as seen from one side, which moves under the guidance by the rollers


30




a


and


30




b


as shown in

FIGS. 3 and 5

.




As shown in

FIG. 3

, the ends of the paired surface-pressure bars


31


, on the side of the cylinder


10


, are connected to each other by a connecting member


32


, those bars and member forming the shape of an upside-down “U” in

FIG. 3. A

block with a T-shaped groove


32


A is fixed to the middle of the connecting member


32


.




As shown in

FIG. 3

, provided on the bottom of the slide block


9


are two protrusions


35


which are positioned to face the block with a T-shaped groove


32


A. By moving the slide block


9


with the cylinder


10


, the position of the moving frame


8


and the slide plate


17


is adjusted and the force of the extending cylinder


10


is transmitted to the surface-pressure bars


31


through the connecting member


32


to actuate the surface-pressure application device. One end of a release jig


33


shown in

FIG. 7

is set in the groove of the block


32


A and the other end is set between the protrusions


35


. Then, the cylinder


10


is contracted to disable the surface-pressure application device. The numeral


36


indicates stoppers to prevent the surface-pressure bars


31


from being pulled out. The numeral


37


is a stopper to position the moving frame


8


(see FIG.


1


).




Surface pressure between the upper plate


6


and the slide plate


17


is effected and lifted as follows.





FIGS. 1

to


4


show the state of the surface pressure effected, that is, of normal casting. The surface-pressure bars


31


are pulled up toward the spring cases


26


. Therefore, the surface-pressure bars


31


are in a stationary state regardless of the extension and contraction of the cylinder


10


and hence the movement of the slide block


9


.




The surface pressure is lifted as follows.




As shown in

FIGS. 7 and 8

, the cylinder


10


is operated to withdraw the cylinder rod


11


almost fully, namely, to position the slide plate


17


near its closing limit. The block with a T-shaped groove


32


A of the connecting member


32


and the protrusions


35


of the slide block


9


are connected to each other by the release jig


33


. Then, the cylinder


10


is operated to withdraw the cylinder rod


11


. Accordingly, the connected member


32


and hence the hook-shaped surface-pressure bars


31


are moved toward the cylinder


10


, i.e., the surface-pressure bars


31


being pulled out, and hence the surface-pressure bars


31


are disengaged from the rollers


28




a


and


28




b


and released from the pulling-up force of the coil springs


25


. Thus, the surface pressure between the upper plate


6


and the slide plate


17


is lifted. Therefore, the guide frame


21


substantially fixed to the frame


5


through the surface-pressure bars


31


and the roller arms


29




a


and


29




b


is separated from the frame


5


. Thus, now the guide frame


21


and the moving frame


8


can be opened by turning them about the pins


22


. The release jig


33


is removed before opening them.




To change the refactories of the factory plates, or the upper plate


6


and the slide plate


17


, the molten-steel vessel


2


is laid on its side, its bottom taking a vertical posture, When the guide frame


21


is turned open about the pins


22


, the moving frame


8


will move downward under its self-weight. However, because the stopper


37


, which is disposed slightly behind the limit to which the moving frame


8


can be moved by the cylinder


10


, stops the moving frame


8


.




On the other hand, the stoppers


36


on the guide frame


21


stop the surface-pressure bars


31


to prevent them from falling. Accordingly, after opening the guide frame


21


, the refractories can be changed in the same way as those of the conventional slide gate.




The surface pressure between the upper plate


6


and the slide plate


17


is effected as follows.




After changing the refractories, the guide frame


21


is turned shut about the pins


22


. Then, as shown in

FIG. 9

, the cylinder rod


11


is protruded to move the slide plate


17


in the closing direction. Accordingly, the protrusions


35


of the slide block


9


push the connecting member


32


through the block with a T-shaped groove


32


A to advance the surface-pressure bars


31


to the left in FIG.


9


. Thus, the surface-preasure bars


31


ride on the rollers


28




a


and


28




b


, and the coil springs


25


exert upward force to push up the surface-preasure bars


31


therough the spring cases


26


, the roller arms


29




a


and


29




b


, and the rollers


28




a


and


28




b


to effect the surface preasure between the upper plate


6


and and the slide bar


17


.




In the above embodiment, the cylinder side of the slide gate comes down when the molten steel vessel


2


is laid on its side, its bottom taking a vertical posture. However, in case that the cylinder side of the slide gate comes up when the molten-steel vessel


2


is laid on its side, the stopper


37


and the stoppers


36


are disposed on the side opposite to the cylinder side to prevent the moving frame


8


and the surface-pressure bars


31


from falling, respectively.




Now, wedge mechanisms to fix the refractory plates


6


and


17


, will be described.




As shown in

FIGS. 10 and 11

, each wedge mechanism comprises a wedge block


38


, a stationary block


39


, a movable block


40


, an adjusting bolt


42


, and a wedge cover


43


. Each of the refractory plates


6


and


17


is fixed by the wedge mechanism and plate dampers


41


which are connected to the movable block


40


by pins. The wedge block


38


is in the shape of a wedge. The stationary block


39


has a recess in the side facing the movable block


40


, and the latter has a recess in the side facing the former, the two recesses forming a wedge-shaped space, wherein the wedgeblock


38


isput. Asshown in

FIG. 1

, in case of the upper plate


6


, the wedge block


38


is driven toward the molten-steel vessel


2


by turning the adjusting bolt


42


in the tightening direction. The wedge block


38


drives the movable block


40


and hence the plate dampers


41


toward the cylinder


10


to fix the upper plate


6


. In case of the slide plate


17


, the wedge block


38


is driven in the opposite direction, leaving the molten-steel vessel


2


behind, and the plate


17


is fixed otherwise in the same way as the upper plate


6


.




To remove the upper plate


6


or the slide plate


17


, the adjusting bolt


42


is turned in the loosening direction. The adjusting bolt


42


pushes up the wedge block


38


through the wedge cover


43


to loosen the movable block


40


and the plate clampers


41


, which release the plate.




In case of the wedge mechanisms for the refractory plates


6


and


17


of

FIG. 12

, the wedge block


38


of each mechanism has a vertical side facing the stationary block


39


and a slant side facing the movable block


40


, but otherwise the mechanisms work in the same way as those in FIG.


11


.




The invention may be embodied in other specific forms without departing from the spirit or essential characteristic thereof. The above embodiment is therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.




INDUSTRAIL APPLICABILTY




The advantages offered by the first aspect of the present invention are as follows. The surface pressure between the refractory plates can be effected by utilizing the cylinder for moving the slidable refractory plate. The cylinder rod pushes the surface-pressure bars so that the bars, of which the front end portions are cut slant on their bottom sides, ride on the rollers which are supported by the roller arms of the spring cases. Accordingly, the coil springs in the spring cases push up the surface-pressure bars to effect the surface pressure between the refractory plates. Then, the surface pressure can be lifted by utilizing the same cylinder. The surface-pressure bars can be pulled back by contracting the cylinder. While the rollers are on the horizontal bottom surfaces of the surface-pressure bars, the bars are under the rolling resistance of the rollers, which however is very small. When the rollers come on the slant bottom surfaces of the front end portions of the bars, the coil springs and the rollers act to push back the bars. Thus, the cylinder for moving the slidable refractory plate can, as it is without raising its driving force or otherwise improving it, be utilized to effect and lift the surface pressure between the refractory plates.




On the other hand, because the slide block is guided by guide grooves and the slide block is connected with the cylinder so that there occur relative slips between them, eccentric bending moment caused by the effecting and the lifting of the surface pressure is not transmitted to the cylinder rod.




Besides, the front end portions of the surface-pressure bars ride on the rollers until their slant bottom surfaces goes beyond the rollers and their horizontal bottom surfaces comes on the rollers. Accordingly, the surface pressure between the refractory plates is always effected at one and the same level. Moreover, the surface pressure can be lifted by setting the release jig between the block with a T-shaped groove of the connecting member and the protrusions of the slide block and contracting the cylinder. Then, the surface pressure can be effected by removing the release jig and extending the cylinder which pushes the surface-pressure bars through the media of said protrusions, said block, and the connecting bar. Accordingly, the surface pressure can be effected and lifted without fail.




The advantage offered by the second aspect of the present invention is that the refractory plates can easily be installed and removed just by turning the adjusting bolts.



Claims
  • 1. A slide gate comprisinga frame fixed to a bottom of a molten-steel vessel, a guide frame attached to a bottom of the frame so as to be openable and closeable, and an upper refractory plate and a lower refractory plate, both refractory plates disposed in a space surrounded by the frame and the guide frame, the lower refractory plate being slidable to control an opening degree of a nozzle gate, wherein: the frame has, on each side, a spring receiver extending in a sliding direction of said lower slidable refractory plate; a spring case, in which coil springs are set, is mounted on each spring receiver; each spring case has, at each end, a pair of roller arms which extend to below the spring receiver and support a roller; a pair of surface-pressure bars are provided such that, when said guide frame is closed, each surface-pressure bar takes a position facing a spring case across the spring receiver and is movable under guidance by the guide frame; the frame and the guide frame are coupled together and the lower slidable refractory plate is pressed to the upper refractory plate by the coil springs to effect surface pressure between them by pressing a protrusion provided on a slide block against a connecting member of the pair of surface-pressure bars and extending a cylinder for sliding the lower slidable refractory plate to engage the surface-pressure bars with the rollers; and a release jig is set between and connects the protrusion of the slide block and the connecting member of the surface-pressure bars and the cylinder is contracted to disengage the surface-pressure bars from the rollers and, thereby, lift said surface pressure.
  • 2. A slide gate as claimed in claim 1 wherein each refractory plate is mounted and removed by using a wedge mechanism with a tapered member and a bolt and turning the bolt.
PCT Information
Filing Document Filing Date Country Kind 102e Date 371c Date
PCT/JP99/00910 WO 00 11/13/2000 11/13/2000
Publishing Document Publishing Date Country Kind
WO00/50188 8/31/2000 WO A
US Referenced Citations (3)
Number Name Date Kind
3501068 Shapland Mar 1970
3587945 Lanatti et al. Jun 1971
3765579 Cramer et al. Oct 1973
Foreign Referenced Citations (1)
Number Date Country
08117985 May 1996 JP