CA1201271A

CA1201271A - Slide gate of a casting ladle or similar container

Info

Publication number: CA1201271A
Application number: CA000446908A
Authority: CA
Inventors: Takumi Nishio; Kazuo Ito
Original assignee: Toshiba Ceramics Co Ltd
Current assignee: Coorstek KK
Priority date: 1983-02-16
Filing date: 1984-02-07
Publication date: 1986-03-04
Also published as: DE3404836C2; FR2540759A1; JPS645992B2; JPS59150656A; FR2540759B1; DE3404836A1

Abstract

SLIDE GATE OF A CASTING LADLE OR SIMILAR CONTAINER

ABSTRACT OF THE DISCLOSURE

Slide gate of a casting ladle or similar container having an outlet aperture for discharging a molten metal accommodated therein, in which the slide gate comprises a slide plate horizontally, slidably disposed at a lower end of the outlet aperture between a first position to block the discharge of the molten metal from the outlet aperture and a second position to allow the discharge of the molten metal from the outlet aperture, the slide plate having a recess extending into the upper face thereof in an area of the upper face which is in alignment with the lower end of the outlet aperture when the slide plate is set at the first position; a gas-permeable refractory member disposed in the recess; and a gas passage element opening into the recess so as to introduce a gas into the outlet aperture through the gas permeable refractory member, can ensure introduction of the gas at a predetermined flow rate into the outlet aperture of the casting ladle or similar container.

Description

This invention concerns a slide gate of a casting ladle or similar container such as a tundish for molten steel or like other molten metal and, particularly, it relates to a slide gate having a gas supply or introduction mechanism.
DESCRIPTION OF THE ACCOMPANYING DR~INGS
hereinafter, the invention will be described in more detail by referring to the accompanying drawings, by which the foregoing and other objects, as well as the features of this invention will be made clearer, in which:
Figure 1 is an explanatory sectional view of an example of a conventional 2-plate slide gate system having a gas introduction mechallism and applied to a casting ladle;
Figure 2 is an explanatory view of cracks developed in ttle conventional slicle plate;
Figure 3 is an explanatory sectional view of a 3-plate - slide gate system having a gas introduction mechanism as a preferred embodiment according to this invention;
Figure 4 is an explanatory sectional view of an essen-tial part of a slide plate in a 2-plate slide gate system as other embodiment according to this invention; and Figure 5 is an explanatory sectional view of an essential part ox a slide plate in a 2-plate slide gate system as a still other embodiment according to this invention.

~3ACKGROUND OF THE INVENTION
A slide gate of a type having a gas supply mechanism for introducing the gas into molten steel accommodated in a casting ladle has been known, for instance, by U.S.
Patent No. 3,581,948.

- 2 -As shown in Figure 1, the conventional slide gate 100 of the type mentioned above comprises a slide plate 104 made of refractory rnaterial and having a generally frusto-conical aperture 103 in which a gas-permeable refractory member 101 also of a frustconical shape is fitted by way ox cement mortar 102, and a gas introduction pipe 108 made of metal and having at its upper end a flanged portion 107 secured to the lower face 105 of the slide plate 104 by way of cement mortar 106. A stationary plate 109 having an aperture 114 aligned with an aperture 113 in the top nozzle 112 situated in a well block 111 of a casting ladle 110 is secured to the bottom of the casting ladle 110 by way of a metal frame member 115. A metal plate or slider 116 is secured to the slide plate 10~ and a submerged nozzle 117 by way of the cement mortar 106. The slide plate 104, the submerged nozzle 117, the gas introduction pipe 108 and the metal plate 116 can be displaced by a driving means (not shown) in a direction A or B between a block position at which the gas-permeable refractory member 101 is opposed to the outlet aperture 118, con-stituted by the apertures 113 and 114, in the casting ladle 110 (shown in Figure 1) and an open position at which an aperture 119 in the slide plate 10~ and an aperture 120 in the submerged nozzle 117 are aligned with the outlet aperture 118. A cut-out portion 121 is formed to the frame member 115 for allowing the submerged nozzle 11.7 and the gas introduction pipe 108 to be displaced in the direction A or B.

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In a case where the slide plate 104 is situated at the block position shown in Figure 1 in the slide gate device 100, a gas introduced from the gas introduction pipe 108 into the output aperture 118 through the gas-permeable refractory member 101 serves to prevent the solidification of molten steel in the aperture 118, remove nonmetallic sludges from the aperture 118 and control the temperature of the molten steel in the casting ladle 110.

However, in the conventional type of slide gate 100, the mortar 106a in a region 123 between the lower face 105 of the refractory slide plate 104 and the upper flange 107 of the gas introduction pipe 108 as well a.s the upper :Eace 122 of the metal plate 1].6 is dr.ied to Norm a gap in the region 123, and there is fear that a part of the gas intro-duced frown the gas introduction pipe 108 may leak through the region 123, for instance, in the direction shown by the arrow C. Such a gas leak will reduce the amount of the gas introduced into the outlet aperture 118 and thus make it insufficient to obtain the above-mentioned effects by the introduction of the gas.
In addition, since the aperture 103 formed in the slide plate 104 so as to receive the gas-permeable refrac-tory member 1~1 therein is in the form of a generally cylindrical penetrating hole, there is fear that cracks 124 rnay be produced by thermal stresses or corrosions due to the molten steel at the periphery of the aperture 119 may reach the aperture 103 as shown in Figure 2 especially when the aperture 103 is situated near the aperture 119.

The cracks 124 may result in a great amount of gas leak to impair the effects attained by the introduction of gas.
Furtnermore, if the cracks 124 should actually develop, it may cause a risk that the gas is blown through the cracks 12~ and the aperture 120 of the nozzle 117 into a mold during discharge of the molten steel from the nozzle 117.
SUMMARY OF THE INVENTION
This invention has been made in view of the foregoinc3 problems and the object thereof is to provide a slide gate capable of ensuring the introduction of a gas at a prede~
terrnined flow rate, with less fear of gas leak, into the outlet aperture oE the casting ladle or similar container.
This object can be attained in accordance with this invention by a slide gate of a casting ladle or similar container having an outlet aperture or discharging a molten metal accommodated therein, in which the slide gate comprises a slide plate horizontally, slidably disposed at a lower end of the outlet aperture for movement between a first position to block the discharge of the molten metal from the outlet aperture and a second position to allow the discharge of the molten metal from the outlet aperture, the slide plate having a recess extending into the upper face thereof, in an area of the upper Eace which is in alignment with the lower end of the outlet aperture when the slide plate is set at the first position; a gas-permeable refractory member disposed in the recess; and a gas passage means opening into the recess so as to introduce a gas into the outlet aperture through the gas permeable refractory member.

DESCRIPTION OF PREFERRED EMBODIMENTS
Figure 3 illustrates a 3-plate slide gate system l as a preferred embodiment according to this invention. The 3-plate slide gate l comprises an upper stationary plate 5.secured to a well block 3 and a top nozzle 4 of a casting ladle or similar container such as a tundish 2 by means of cement mortar or the like, a lower stationary plate 6, a submerged nozzle 7, both ox the lower stationary plate 6 and the submerged nozzle 7 being supported by adequa-te support means (not shown) so as to be stationary relative to the upper stationary plate 5, and a slide plate 8 slidable to the upper and lower stationary plates 5, 6 in the direction D or E. An outlet aperture 12 comprising a hole 10 in the top nozzle 4 continuously extended from an aperture 9 in the well block 3 and an aperture il in the upper stationary plate 5 is vertically aligned with an aperture 13 in the lower stationary plate 6 and an aperture la in the submerged nozzle 7~
The slide plate 8 has a penetrating hole 15 allowing the discharge of molten metal such as molten steel accommodated in the casting ladle through the outlet aperture 12, as well as a recess 17 and a lateral penetrating hole 18 communicated with the recess 17 constituting a gas introduction mechanism 16. The recess 17 is opened at the upper face of the slide plate 8 so as to be able to be opposed to an lower end of the Il 2~a~27~

outlet aperture 12 and is closed at the lower face side of the slide plate 8. A metal member l9 is secured by means of cement mortar to the bottom wall of the recess 17. A gas-permeable refractory member 20 is secured by means of cement mortar to the inside of the recess 17 above the metal member 19. The metal member l9 is formed on a circumferential edge thereof with an annular upward protruding portion 21, and the protrusion 21 is fitted and fixed to a complementary circular or annular step or depression 27 of the gas-permeable refractory member 20 by means of cement mortar so as to define a disc-like space 24 between a lower face 22 of the gas-permeable refractory member 20 and an upper face 23 of the metal member 19, as well as to make an upper face 25 of the gas-permeable refractory member 20 in flush with the upper face 26 of the slide plate 8. The sectional shape of the recess 17 and of the members 19 and 20 just fitted in the recess 17 may be any other configurations such as a polygonal shape instead of a circle.
The lateral hole 18 formed in the slide plate 8 opens at one end thereof to a lower portion of the circumferential wall or surface 28 of the recess 17 and opens at the other end thereof to one end face 29 of the slide plate 8 crossing in perpendicular to the sliding directions D, E of the slide plate 8. A metal pipe 30 for gas introduction is fitted and fixed gas-tightly in the lateral hole 18 by means of cement mortar.
The inserted end 30a of the metal pipe 30 protrudes into the recess 17 so as to oppose to the space 24 in the recess 17 and is firmly fitted to the aperture l9a in the metal member 19.

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The gas introduction mechanism 16 c:omprises the recess 17, the gas-permeable refractory member 20, the metal member 19 and the gas introduction pipe 30 fitted in the lateral hole 18, and the gas passage means for the yas introduction comprises the gas introduction pipe 30 fitted in the lateral hole 18. The leading end 19a of -the gas introduction pipe 30 may be fitted in the lateral hole 18 instead of being protruded into the recess 17. In this case, the pipe 30 and the lateral hole 18 con sti-tute the gas passage means. Further, the leading open end l9a of the gas introduction pipe 30 may be communicated with the hole 18 a-t the end face 29 of the slide pla-te 8 by way of a metal support frame 31 or the like in a gas-tight manner instead of being fitted in the hole 18. In this case, the gas passage means is substantially composed of the hole 18.
Although the provision of the metal member 19 is not always necessary, it is preferred to engage and fix the gas-permeable refractory member 20 to the recess 17 in such a way that the space 2~ is formed below the lower face 22 of the gas-permeable refractory member 20 in order to introduce the gas from the gas passage means toward a side of the lower face 22 of the member 20. Instead of forming the space 24, a lateralhole of a relatively large diameter may be provided in a lower portion of the gas-permeable refractory member 20 to introduce the gas from the gas passage means through the lateral hole.
The gas introduction pipe 30 may be made of refractory material instead of metal provided that sufficient heat-L27~L

resistivity, mechanical toughness or strength or the like can beexpected.
A displacing means 32 such as a hydraulic cylinder is provided for displacing the slide plate 8 in the direction D or E between the position where the aperture 15 aligns with the apertures 12, 13 and 14 and the position where the gas-permeable refractory member 20 opposes to the aperture 12 (the position shown in Figure 3).
The well block 3, the nozzles 4, 7 and the plates S, 6, 8 are made of refractory material, for instance, comprising by weight oP alumina and lO % by weight of silica in -this embodiment but any other conventional refractory materials rnay be used.
The slide gate 1 having thus been constituted is operated in the rnanner described below.
Upon closing the outlet aperture 12 of the casting ladle 2, the slide plate 8 is displaced slidingly by the cylinder device 32 in the direction D to a predetermined position at which the gas-permeable refractory member 20 of the gas intro-duction mechanism 16 just opposes to the outlet aperture 12 lshown in Figure 3). A gas, heated to a predetermined tempera-ture if desired, is supplied from a gas supply means such as a pump [not shown) to the pipe 30 in the direction F. The gas may be an inert gas such as nitrogen or argon and, if desired, oxygen or air. The gas fed to the pipe 30 is introduced from the opening at the end 30a of the pipe 30 into -the space 24 in the `"I
~,~ ~4 recess 17 and then through the gas-permeable reiractory member 20 into the outlet aperture 12. The gas thus introduced or blown into the outle-t aperture 12 gives various effects. For instance, it causes the molten steel in the outlet aperture 12 to flow upwardly out of the aperture 12 thereby preven-t the solidification of the molten steel in the outlet aperture 12, as well as removes nonmetal impurities or sludges from the aperture 12 to the upper part of the ladle 2 by the upward flow of the gas passing through the aperture 12.

In the slide gate 1, since the recess 17 of the slide plate 8 opens substantially only at the upper end thereof, the gas entering the recess 17 flows through the gas-permeable refractory member 20 toward the upper or open end of the recess 17, therefore substantially all the gas supplied through the pipe 30 can be introduced or blown at a predetermined flow rate into the outlet aperture 12~
Furthermore, in the slide gate 1, since the gas-permeable refractory member 20 is disposed in the recess 17 having the bottom wall, there is li-ttle fear tha-t cracks may be developed over the entire part of the slide plate 8.
Upon discharging the molten steel from the casting ladle 2, the slide plate 8 is displaced slidingly by the actuation of the cylinder device 32 in the direction E to a predetermined position at which the aperture 15 in the slide plate 8 is aligned with the apertures 12, 13, 14.
In the slide gate 1, since the gas introduction pipe 30 is extended in perpendicular to the end face 29 of the slide plate 8 and along the sliding direction D, E of the slide plate 8, the gas introduction pipe 30 can be moved into and out of the space 8a between the pla-tes 5, 6 accompanying the displacement of the slide plate 8 in the direction D or E and, accordingly, no additional space or recess such a portion 121 of Figure 1 is required for the movement of the gas introduction pipe 30.
The slide gate 1 is constituted in the form of a

3 plate slide gate system in this embodiment but it may be in the form of a 2-plate system in which the plate 6 ancl the submerged nozzle 7 are made movable integrally with the slide plate 8 in the direction D or E. That is, the slide gate 1 may be constituted as a 2-plate slide gate system similar to the slide gate shown in Figure 1 in which the slide plate 104 and the gas introduction mechanism in Figure 1 is replaced with the slide plate 3 and the gas introduction mechanism 16 shown in Figure 3, In this case an appropriate cut-out portion will be formed in the frame 115 to pass the pipe 30 therethrough.

In the case of a 2-plate slide gate system, a gas introduction pipe 33 may be disposed through the bo-ttom wall 36 of the recess 35 in a slide plate 34 as shown in Figure 4, in which members or components similar to those in Figures 1 and 3 carry the same reference numerals. In Figure.4, a member 37 similar to the metal member 19 of Fiyure 3 has a central opening 38, and the upper end 39 of a gas introduction pipe 33 is firmly fitted in the opening 38 of the metal member 37 as Z7~

a flange. Cement mortar 47 is filled to ensure gas-tight seals between a circumferential wall 40 of the recess 35 and a circumferential surface 41 of the gas permeable refractory member 20, and between the circumferential wall 40 of the recess 35 and an outer circumferential surface 42 of the petal member 37, as well as between an upper face 43 of the bottom wall 36 of the recess 35 and a lower face 44 of the metal member 37 and between the circumferential wall of the aperture 45 in the slide plate 34 and an outer circumferential surface 46 of the gas introduction pipe 33.

The slide plate 34 is made slidable relati.ve to a frame member 115 in thy direction vertical to the plane of the drawing paper of Figure 4 and, when it is set at a predetermined position at which the gas-permeable member 20 opposes to the outlet aperture 118 (Figure 1), the discharge of the molten steel is blocked and the gas is blown into the outlet aperture 118.
Since the gas introduc-tion pipe 33 opens to the recess 35 in this slide plate, mortar sealing is formed over a longer region and the fear of gas leak can be reduced or the amount of gas leak, if any, can be decreased. In addition, since the slide plate 34 is reinforced with the metal member 37 and the gas introduction pipe 33, there is less fear of : developing large cracks in the slide plate 34.
As shown in Figure 5, the thickness of the bottom wall 49 of the recess 35 may be increased and a thick metal plate 7~

51 may be secured to the lower face of a refractory slide plate member 50 in order to increase the strength of the slide plate 48 at the portion near the recess 35. The slide plate 48 can be displaced relative to the metal frame member 115 (not shown in Figure 5) in the direction vertical to the plane of the drawing paper of Figure 5 in the same manner as the slide plate 34 shown in Figure 4.
In the slide gate according to this invention, the gas may be.blown into the molten steel between the sliding surfaces even when the molten steel is being d.ischarged as well as during the interruption of the discharge of the molten steel. Further, the gas flow may also be given upon transfer or displacement of the slide plate so as to reduce the frictional resistance at the s ding surfac s.

Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

l. Slide gate of a casting ladle or similar container having an outlet aperture for discharging a molten metal accommodated therein, in which the slide gate comprises a slide plate horizontally, slidably disposed at a lower end of the outlet aperture and movable between a first position to block the discharge of the molten metal from the outlet aperture and a second position to allow the discharge of the molten metal from the outlet aper-ture, the slide plate having a recess extending into the upper face thereof in an area of the upper face which is in alignment with the lower end of the outlet aperture when the slide plate is set at the first position;
a gas-permeable refractory member disposed in the recess; and a gas passage means opening into the recess so as to introduce a gas into the outlet aperture through the gas permeable refractory member.
2. The slide gate of claim 1, in which the gas passage means opens into the recess at a lower portion thereof.
3. The slide gate of claim 2, in which the gas passage means includes a hole extending horizontally through the slide plate from the lower portion of the recess to an end face of the slide plate.
4. The slide gate of claim 3, in which said end face is perpendicular to said hole.
5. The slide gate of claim 4, in which the gas passage means comprises a gas pipe connected to said horizontal hole.
6. The slide gate of claim 5, in which the gas pipe extends through the horizontal hole to the recess.
7. The slide gate of claim 6, in which the open end of the gas pipe protrudes into the recess.
8. The slide gate of claim 7, in which a metal plate is disposed on a bottom wall of the recess.
9. The slide gate of claim 8, in which the protruding end of the gas pipe is fixed to the metal plate.
10. The slide gate of claim 9, in which the gas permeable refractory member positioned relative to the metal plate so as to define a space between a lower face of the gas permeable refractory member and an upper face of the metal pipe in communication with the open end of the gas pipe.
11. The slide gate of claim 1, in which the slide gate is a 3-plate type slide gate.
12. The slide gate of claim 1, in which the slide gate is a 2-plate type slide gate.
13. The slide gate of claim 1, in which the gas passage means has an end opened at an area between a lower face of the gas-permeable refractory member and a bottom wall of the recess.
14. The slide gate of claim 13, in which the gas passage means comprises a hole penetrating the slide plate from the bottom of the recess to a lower face of the slide plate and a gas pipe fitted in the said hole in a gas-tight manner.
15. The slide gate of claim 14, in which the gas pipe has a flange integrally formed at the open end thereof and cement means provides a gas-tight sealing between a lower face of the flange and the bottom wall of the recess.
16. The slide gate of claim 15, in which the flange is formed so as to extend over an entire part of the bottom wall of the recess.
17. The slide gate of claim 16, in which the flange has an upwardly extending periphery and the gas permeable refractroy member has a complementary depressed portion at the lower face thereof which mates with the protruding portion of the flange.
18. The slide gate of claim 13, in which the slide plate has an increased wall thickness at a portion where the recess is provided.