JPS61103656A - Molten-metal flow control nozzle for continuous casting and method of controlling molten-metal flow - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to continuous casting processes for continuously forming elongated castings from molten metal, namely Ga, and more particularly to apparatus and methods for controlling the flow rate of the molten metal during continuous casting. .

In conventional quick casting methods, a constant flow of molten metal is forced from a tundish through an elongated conduit in a refractory nozzle into a quick casting mold located below. Many devices are known to control or stop the melt flow during this operation.

For example, U.S. Pat. No. 2,005,311 describes a method for controlling the flow of water from an outflow orifice in the underside of the ladle using a stopper rod located within the ladle. However, this device suffers from the cost and structural complexity of a fairly large number of moving parts, and the stopper ζ rod corrodes in Toripe's harsh environment, introducing unwanted contamination into the island. However, it has the disadvantage of limiting the casting operation time.

A second known device for controlling melt flow during continuous casting includes a sliding gate valve on the outer surface of the ladle exit orifice, which can be moved mechanically to limit or stop the melt flow. do. However, this sliding gate valve has the disadvantage that the refractory plate corrodes during use, and this corrosion introduces undesirable contaminants into the molten metal, eventually requiring the casting operation to be stopped and replaced.

Melt! & A third known method of restricting flow is.

This is a method of obtaining a predetermined flow of molten metal by using a refractory nozzle with a nozzle hole with a very precisely finished inner hole and maintaining a constant static pressure on the molten metal. However, this control method
The inner surface of the refractory nozzle corrodes and it is difficult to maintain a constant static pressure of the molten metal! The downside is that it's unsightly. Also, this method does not provide a suitable mechanism for quickly stopping the G-island flow in the event of an emergency during a casting operation.

There is a need in the industry for a bath light control system and method that does not have the drawbacks described above.

SUMMARY OF THE INVENTION The present invention provides a novel method and apparatus for controlling molten metal flow during continuous casting, which is simple in construction, solves corrosion problems and increases the production time. Maintaining a constant casting speed improves the metal properties of the casting, and has the added benefit of easily stopping the melt flow in the event of an emergency. The molten metal flow control device of the present invention applies a sufficiently large fluid pressure vcl to the flowing molten metal by a controlled amount.

It has a device for controlling and stopping the flow of molten metal from the upper container 1, such as a ladle or tundish, to the lower container 1, such as a tamp or mold. This bath light control device has a refractory nozzle member having five quarters through which selected flow control fluids are transmitted. The fluid source pressurizes the selected fluid and pumps it to the refractory nozzle member.

Fluid permeates in a controlled amount into the nozzle bore through the permeable portion of the nozzle, forming a flow rate 1 tl controlling fluid barrier within the nozzle bore. Therefore, the flow of molten metal is preferably controlled by controlling the pressure and amount of the selected fluid supplied to the refractory nozzle member. In a preferred embodiment of the invention, a fluid manifold is formed around or within the refractory nozzle member, and an inert gas is used as the flow and discharge fluid. Implementation of the present invention eliminates the need for stopper rods, sliding gate valves, or nozzles with precision-finished holes previously used on the melt flow side, thus eliminating the deficiencies associated therewith.

In the continuous casting process 1f4a shown in Figure 1, a molten steel supply source 10 in a ladle 12 lined with a fireproof metal is used. Molten steel is injected from the ladle 12 into the tundish 18 via a nozzle 14 and a wall beating shroud 16. The +8 steel in the tundish 18 is then fed to the continuous a production mold 20 through the nozzle 22 and shroud 24, preferably to a level below the upper surface of the two steels in the mold.

After being introduced into the continuous casting mold 20, the common A begins to solidify as K flows into the mold 20, and first the outer part of the MM solidifies to form a shell. The molten steel adjacent to the inside of the mold 20 is retained within this outer well even after the masonry is evacuated from the mold and completely solidifies upon cooling. Therefore, control over the rate of progress of this operation is important for good results t4.

To further explain FIG. 1, the speed of GS supplied from the ladle 12 to the tundish 18 is suitably controlled by 1 itlJ by the operation:C of the flow rate control device 26 of the present invention. Similarly, the molten steel equipment supplied from the tundish 18 to the mold 20 is also supplied to the second stream 'N' disposed between the two.
Preferably controlled by using the mlJ # device 26.

Figure 2 shows the flow rate control nK connected to the tanditshu 18.
Details of device i26 are shown. This flow rate control device 26
The operation and structure of will be described with respect to this connection, but of course this control device can also be applied to control the flow rate from the ladle 12.

Flow control device 26 according to a first embodiment of the invention includes fluid supply 11M28. Fluid pressure side tilting device 30. and appropriate nozzle 2
2 includes a fluid supply tube 32 fixed to the outer surface of 2. Nozzle 2
2 is made of fireproof storage.

Also, it is placed inside the tap-in-sea J-18 and extends downward to form a nozzle hole, that is, an outflow passage 34 inside. The outer periphery of the lower end of the nozzle 22 is surrounded by a metal casing 36, and this casing includes a fluid common pipe 32.
is properly fixed. An inflow boat 38 is provided in the main body of the nozzle 22 and connects the fluid supply kidney 32 with a fluid manifold 40 formed on the peripheral wall of the main body of the nozzle 22 .

In operation, the flow control device 26 controls the 1m steel flow: l1l
The flow rate of molten steel in the outlet passageway 34 is controlled by adjusting the degree of restriction of the fluid barrier.

This adjustment is accomplished by adjusting the pressure of the selected fluid from fluid supply #28 to the fluid manifold within nozzle 22. At least the nozzle portion between the fluid manifold 40 and the outflow passage 34 has a selected fluid under control [7]
[Made of a porous, i.e. fluid permeable, refractory material that can pass through IpA.

Although not limited to, the nozzle 22 may be made of aluminum oxide.

It is formed of zirconium oxide, magnesium oxide, alumina-graphite, zirconia-graphite, or a mixture thereof.

The porous portion of nozzle 22 preferably has a porosity of about 12 to 30%, with an average pore size of about 1.18X, to
x o m), t to about 1.57 x 10-''3 inches (4 x 10-3-3). and the average pore size will vary depending on the type of fluid selected, the magnitude of this pressure, and the dimensions of the outlet passageway 34. Continuously, the inert gas as the flow control fluid is preferably argon or nitrogen.

Although not limiting the present invention, the degree of restriction of the fluid barrier generated in the outflow passage 34 used in the implementation VC of the present invention is maintained uniformly with respect to the outflow passage 341C, and has no influence on the stone flow direction. It is desirable that there is no such thing. For example, in Figure 2,
Since the outflow channel 34 is substantially cylindrical, the path of the molten steel flow through this channel is aligned with the central axis of the outflow channel 34, i.e. it is ensured that the deflection 1, e.g., does not widen with respect to the axis, due to the effect of the fluid barrier mentioned above. suitable. Accordingly, in the embodiment of FIG. 2, the fluid permeability of the nozzle portion between manifold 38 and outlet passageway 34 is uniform, forming a generally annular fluid barrier around outlet passageway 34, which fluid barrier provides T
It is preferable to limit the surface immersion of the flow control passage without changing the flow control direction of the a steel. Hands-on a work.

The fluid barrier of the present invention has a falling melt J! It has been confirmed that minimizing the curved descending passage that normally occurs in the fourth flow, so-called "snaking 6," has the effect of stabilizing the M adjustment flow discharged from the outflow passage 34.If the flow rate needs to be reduced, In this case, a large fluid pressure is applied to increase the size of the ring and fluid wall, and when this pressure is further increased, the outflow passage 34 is closed and the flow of molten steel is interrupted.

As described above, the practice of the present invention avoids many of the serious deficiencies present in conventional methods of controlling metal flow during continuous casting. For example, one example of mechanical groove making using the device of the present invention! @For the matter.

Grooving of equipment using conventional stopper rods and sliding gate valves? M: The problem of miscellaneousness does not occur. According to the present invention, the flow rate of the t-hole can be controlled in a cumulative manner by a simple operation while adjusting the fluid pressure valve. The present invention also eliminates the corrosion problems associated with stopper rods and sliding gate valves.

Therefore, continuous casting operation for a long time is possible.

Furthermore, since the fluid flows through the area limited by the fluid barrier formed in the outflow passage 34, the life of the nozzle 22 is extended, and the problems of corrosion caused by melting and direct contact with refractory storage are avoided. can be minimized. Finally, by selecting argon or nitrogen as the fluid used in the practice of the present invention, molten metal is generated during passage through the outlet passageway 34 of the nozzle 22. Undesirable oxidation can be minimized.

EXAMPLE 1 A nozzle 22 as shown in FIG. 2 is made of a silcony-graphite composition and has a vertical dimension of 4 inches (100 ii).

A lower cylindrical portion formed an outflow passage 34 having a diameter of 0.54 inch (13, s). The wall thickness of the nozzle 22 is approximately 1 inch (25ffiI+): 0.28 inch (7, Q
The uniform porosity over the entire length is approximately 15%.
-17%, the average pore size is about 1.38-1.58 X 1
0''''5 inches (3,5-4X10-').

A gas manifold 40i is provided in the wall portion of the nozzle 22 to form an elongated annular space.

The manifold was spaced a uniform distance from the outlet passageway 34 by about 0.33 inches (8.25!131) and had a thickness of about 0.04" (1.0 inches).

A tandit 7 unit 18 similar to that shown in FIG.
Three outlets were provided for continuous casting with a stream of molten metal. A nozzle 22 having features of the present invention is secured to the tundish 18 for controlling melt flow through one of the outlets, and replaces a conventional precision dimension hole nozzle with controlling melt flow through the other two outlets. Therefore, it stuck to the tundish 18.

No shroud 24 was used and the molten metal flow was allowed to fall freely into the mold 20.

As before, after preheating the nozzle and other parts of the casting machine, one cast of steel is cast at a temperature of 2935"F (1613C) in the caster 12 and a temperature of 2830"P (1554C) in the tundish 18. Started casting. The nozzle 22 is initially
It was operated in the conventional non-pressurized fluid mode, but argon was supplied under pressure to the nozzle 22 several minutes after the start of casting. After a short time the flow of molten steel through the nozzle 22 decreased considerably and finally stopped completely. The argon pressure was then reduced and flow of molten steel through nozzle 22 resumed. A stable and constant flow of molten steel was obtained by continuous adjustment of the argon supply. Specifically, the casting speed of 42 inches per minute was maintained without fluctuation, while the casting speed of the other two nozzles was constantly varied between 40 and 50 inches per minute. Ta. Maintaining even casting speed is highly desirable since variations in casting speed can cause undesirable changes in metallurgy due to differences in the cooling rates of different parts of the casting. The practice of the present invention resulted in approximately constant casting speeds and correspondingly uniform shell castings. Before the above test was completed, a rope for four people was cast, but the test passing through nozzle 22
Steel is cast in the correct flow state, i.e. with less deflection □
The molten metal stream entering the mold and exiting nozzle 22 had a bright color, indicating undesirable oxidation resistance.

Nozzle 22 was removed and observed and showed no signs of erosion according to the above test.

Test 2 A nozzle 22 similar to that used in Test 1 above was used in this test, with a shroud 24 fixed to the bottom of the nozzle to introduce the flow of molten metal into the mold. Similar to test 1,
Casting was started with three streams of molten metal at a ladle temperature of 2935'F (1613°C) and a tundish temperature of 2850°C (1566°C). After starting casting.

Argon is supplied to the nozzles 22 and each nozzle is supplied with argon at a rate of approximately 5
The casting speed was maintained at inches. The casting rate of the melt stream through nozzle 22 was then reduced to 940 inches per minute by gradually increasing the argon pressure. Next, nozzle 22
Reduce the argon pressure and reduce the casting speed to 50 ml per minute again.
It increased to an inch.

The accurate measurement equipment for argon pressure and melt flow rate used in each of the tests described above was such that argon was supplied from a room temperature source to the nozzle 22.
It was not used because of the large temperature rise it experienced during the first casting period.

Second Embodiment A second embodiment of the flow control device 26 shown in FIG. 3 includes a refractory nozzle 42 having a ratted outlet passage 42. The outside of the nozzle 42 is surrounded by a metal casing 46 having an open annular space spaced a small distance therefrom to form a fluid manifold 48 around the nozzle. A fluid supply v32 is secured to the metal casing 46 and connects the fluid supply to the fluid manifold 48.

Nozzle 42 is made of one of the various refractory compositions described above and has a substantially uniform porosity and average pore size within the ranges described above.

In operation, a selected fluid is supplied to the fluid manifold 46 at a selected pressure and passes through the wall portion of the fluid knee nozzle 42 to form an annular fluid barrier within the outlet passageway 44 and prevent the flow of molten metal therein. ■1] Reject. metal casing 4
6 must be made of a suitable material to withstand the high temperatures to which the portion adjacent the upper edge will be subjected.

Third Embodiment Nozzle 5 of the third embodiment of the flow rate control device 26 shown in FIG.
2 is made of a plurality of refractory materials and has a VT flow passageway 54. Nozzle 52 has an internal fluid manifold 56;
Pressurized fluid is supplied from an inlet boat 58 connected to the fluid supply pipe 32 . The wall portion of the nozzle 52 is on the outer surface of the nozzle 52! fs is formed by the first refractory section 60 in contact with the first refractory section 60 and the M22 ignition 62 between the fluid manifold 56 and the outflow passage 54. Since the first refractory section 60 has a relatively low fluid permeability, and the second refractory section 62 has a relatively high fluid permeability, the pressurized fluid in the manifold 56 permeates into the outflow passage 54. A fluid barrier according to the present invention is formed on the flow rate side (to). Although the present invention is not limited to this, the first ignition section 60 can be made of an alumina-graphite composition, and the second ignition section 62 can be made of a zirconia-graphite composition. Also, the nozzle 52 of this embodiment is preferably enclosed in a metal casing 64.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional side view of a continuous casting apparatus having the features of the present invention; FIG. 2 is a side cross-sectional view of a refractory nozzle having a device for controlling the internal molten metal flow; FIG. Fig. 4 is a side sectional view of a third embodiment of a refractory nozzle having a device for controlling internal molten metal flow. . 12... Tribe, 14... Nozzle, 1
6... Nyuroud, 18... Tundish, 20... Mold, 22... Nozzle, 2
4... Shroud. 26... Stone flow control device, 28... Fluid supply source,
C32... Fluid supply pipe, 34... Molten metal outflow passage. 40... Fluid manifold, 56... Fluid manifold, 60... First fireproof section, 62... Second
Fireproof part 30...Fluid pressure control device FIG, 3

Claims (1)

[Claims] 1. A molten metal flow control nozzle used in a continuous casting device in which molten metal is fed from an upper vessel to a lower vessel via an intermediate nozzle member: Large enough to control the feed rate of the molten metal 1. A molten metal flow control nozzle comprising a control device for applying a fluid pressure of 1 to the molten metal in a controlled manner. 2. In the nozzle described in item 1 above, the device for applying fluid pressure comprises: a fluid supply source; a fluid pressure adjustment device disposed adjacent to the molten metal outflow passage between the upper container and the lower container; the fluid supply source and a device for controlling the pressure supplied to the fluid pressure regulating device to control the melt supply rate. 3. The nozzle according to item 2 above, wherein the nozzle member is made of a refractory composition and includes a molten metal outflow passage extending between the upper container and the lower container, and the fluid pressure regulating device is configured to control the molten metal outflow passage. a fluid permeable portion of the surrounding nozzle member;
A molten metal flow control nozzle in which the fluid passing through the fluid permeation portion forms a fluid barrier against the molten metal flow in the molten metal outflow passage to control the molten metal flow. 4. The molten metal flow control nozzle according to item 1 above, wherein the fluid is an inert gas. 5. The molten metal flow control nozzle according to item 4 above, wherein the fluid is argon or nitrogen. 6. The nozzle according to item 5 above, wherein the refractory composition of the nozzle member is a molten metal flow selected from the group consisting of aluminum oxide, zirconium oxide, magnesium oxide, alumina-graphite, zirconia-graphite, and mixtures thereof. control nozzle. 7. The nozzle according to item 6 above, wherein the fluid permeable portion of the nozzle member has a porosity of about 12 to 30% and an average pore diameter of about 1.
18 x 10^-^5 inches (3 microns) to 1.5
Molten metal flow control nozzle that is 7 x 10^-^3 inches (40 microns). 8. In the nozzle according to item 7 above, the molten metal outflow passage adjacent to the fluid permeation part has a cylindrical shape, the fluid permeability of the fluid transmission part is substantially uniform around the molten metal outflow passage, and the molten metal outflow passage adjacent to the fluid transmission part has a cylindrical shape. Molten metal flow control nozzle that forms a nearly uniform annular fluid barrier around the periphery. 9. The nozzle of claim 8, wherein the fluid pressure regulating device further includes a fluid manifold surrounding the fluid permeable portion of the nozzle member. 10. The molten metal flow control nozzle according to item 9 above, wherein the fluid manifold is formed inside the nozzle member. 11. The nozzle according to item 10 above, wherein the fluid permeable portion of the nozzle member is made of a first refractory composition having a relatively high fluid permeability, and the other portion of the nozzle member is made of a first refractory composition having a relatively low fluid permeability. 2 Molten metal flow control nozzle composed of refractory composition. 12. The molten metal flow control nozzle according to item 11 above, wherein the upper container is a tundish, the lower container is a casting chamber, and the molten metal is a ferrous metal or a non-ferrous metal. 13. In a method for controlling the melt flow in continuous casting, in which the melt is supplied from the upper vessel to the lower vessel through the melt outlet passages, i.e. holes, in intermediate nozzle members: at least one of the intermediate nozzle members adjacent to said hole; a portion of the intermediate nozzle member of a selected fluid permeable refractory material; A method of controlling the flow of molten metal, including the process of pumping at a certain pressure and volume; 14. In the method of item 13 above, a fluid permeable portion of the intermediate nozzle member is formed around a selected portion of the nozzle hole, and a selected fluid is pumped through the selected portion at a substantially uniform pressure and volume to transport the molten metal. A method of controlling the flow of molten metal to maintain it away from the nozzle hole. 15. A molten metal flow control method in which the pressure and amount of the selected fluid pumped into the nozzle hole are increased to decrease the molten metal flow rate using the method described in item 14 above. 16. A molten metal flow control method in which the pressure and amount of the selected fluid pumped into the nozzle hole are increased to increase the molten metal flow rate, using the method described in item 14 above. 17. Molten metal flow control method according to item 14 above, wherein the fluid-permeable refractory material is selected from the group consisting of aluminum oxide, zirconium oxide, magnesium oxide, alumina-graphite, zirconia-graphite, and mixtures thereof. . 18. The molten metal flow control method according to the above item 17, wherein the selected fluid is an inert gas. 19. The molten metal flow control method according to item 18 above, wherein the selected gas is argon or nitrogen. 20. In the method described in item 14 above, the fluid permeable portion of the nozzle hole has a porosity of about 12 to 30% and an average pore diameter of about 1.
18 x 10^-^3 inches (3 microns) to 1.5
Molten metal flow control method to form 7 x 10^-^3 inches (40 microns). 21. The molten metal flow control method according to item 20 above, wherein the upper container is a tundish and the lower container is a continuous casting mold.