JPH04327365A - Method for preventing flow-out of slag from molten metal holding vessel - Google Patents

Abstract

PURPOSE:To prevent the whole eddy flow containing inclining voltex by widening the periphery of a pouring hole at the bottom part in the holding vessel in the height direction to make this conical tapered shape downward and charging a float having a yoke extended downward from the center in the specific condition. CONSTITUTION:The periphery of pouring hole 1 at the bottom part in the holding vessel is widened in the height direction and made to the conical tapered shape 3 downward, and the lower tip part of the yoke 2 in the float 1 is inserted into inside the tapered shape part 3 so as to satisfy the following condition. 1.5<=Df, 2.5<=Dt<=12d, 2ri<=Dt, 2d<=hi<=ht+2(hf+lf), wherein, d: diameter of the pouring hole, Dt: the max. dia. of the tapered shape part, ht: height of the tapered shape part, Df: diameter of cross section in interface between molten metal and slag, hf: distance in vertical direction between lower end of the float body and interface of the molten metal/slag, lf: length of the yoke part in the float, ri: horizontal distance between the float center and the pouring hole center and di: vertical distance between the interface of molten metal/slag and the pouring hole.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for preventing slag from flowing out at the end of pouring when molten metal is discharged from a holding container and poured into another container.

0002

[Prior Art] In molten metal refining and casting processes, when molten metal is discharged from a holding container and poured into another container, slag leakage at the end of pouring greatly impairs the cleanliness of the cast metal, so there is a method to prevent this. Various attempts have been made. The main cause of slag outflow at the end of pouring is entrainment by vortices generated between the pouring port and the molten metal/slag interface.

[0003] As a countermeasure to this problem, a method of fixing a stopper directly above the pouring spout in order to prevent the generation of vortices (Japanese Patent Laid-Open No. 53-3
No. 9221), and a method of floating a float on the interface between the molten metal and slag directly above the pouring port (Japanese Patent Laid-Open No. 60
210352), and these are the simplest and most direct methods of locating an obstacle at the location where the vortex is generated. However, in the former method, a vortex called an inclined vortex is generated from the side of the fixed stopper, and this vortex entrains the slag. In order to prevent this, it is necessary to increase the diameter of the stopper and to make the distance between the stopper and the pouring hole extremely small, which makes it difficult to ensure a sufficient pouring speed.

In the latter method, due to the phenomenon that the float moves by itself to the center of the rotational force generated at the location where the vortex is generated,
It has the advantage of being able to prevent tilted vortices that occur at positions away from directly above the pouring spout, but stably positioning the float near the pouring spout before vortices occur is a problem that can occur in the container due to convection, etc. This is difficult due to the current, and as a countermeasure to this problem, the float is suspended from above on a chain or the like, and the tension is used to stabilize the float's position. However, this obstructs the free movement of the float toward the center of the rotational force at the vortex generation point. In addition, a control system is required to lower the float in accordance with the lowering of the molten metal/slag interface while applying tension to the float, thereby detracting from the original advantage of being a simple method.

[0005]

[Problems to be Solved by the Invention] As described above, in the conventional slag cutting method using a float, in order to stably position the float directly above the pouring port, the float is suspended from above with a chain, etc. However, this method obstructs the free movement of the float toward the center of rotational force at the point where the vortex is generated, halving the effect of preventing tilted vortices. There was a problem in that a control system was required to lower the pressure according to the decrease in the temperature, and a complicated device was required.

[0006] An object of the present invention is to provide a slag cutting method that allows the float to float freely without applying force, stabilizes its position directly above the pouring hole, and prevents vortex generation.

[0007]

[Means for Solving the Problems] In the present invention, when discharging and pouring molten metal from a holding container into another container, a pouring hole with a diameter d is provided at the bottom of the holding container, and the periphery of the pouring hole is When widened in the height direction and formed into a cone-like tapered shape having a maximum diameter Dt and a height ht, at the end of pouring, the molten metal in the holding container is exposed to the rudder rod extending downward from the main body and its center. This is a method for preventing slag outflow from a molten metal holding container, which is characterized in that a float is introduced under conditions satisfying Equations 1 to 4.

1.5d<Df
...(Math. 1) 2.5d<Dt<12d
...(Math 2) 2ri
<Dt...(Math. 3) 2d<hi <ht +2(hf +lf)
...(Equation 4) Furthermore, in the present invention, the diameter of the lower end of the float body is made smaller than the maximum diameter Dt of the tapered part, and the diameter dt of the float rudder is made smaller than the diameter d of the pouring port. In this method, the outer surface of the float body and the inner surface of the tapered portion form a stopper to automatically terminate pouring of molten metal.

However, Df: Diameter of the cross section of the float body at the interface between the molten metal and slag hf: Vertical distance between the lower end of the float body and the molten metal/slag interface lf: Length of the float rudder bar ri: Float Horizontal distance hi between the center of the float and the center of the spout at the time of charging: This is the distance in the vertical direction between the molten metal/slag interface and the spout when the float is charged.

0010

[Function] According to the present invention, an example of which is shown in FIG. 1, by inserting the lower tip of the rudder rod 2 of the float 1 with rudder rod 2 into the inside of the tapered portion 3 around the pouring spout 4,
That is, by setting 2ri <Dt, the center of the float 1 with the rudder rod 2 is the diameter D of the widest part of the tapered portion 3.
It no longer moves outward beyond t, and therefore its position can be stabilized in the vicinity directly above the spout. In addition, since no force such as hanging support is applied to the float 1 with the rudder 2, it can move freely to the center of the rotational force generated at the location where the vortex 8 is generated, as shown in Figure 2, and all of the vortices including the inclined vortices are It becomes possible to prevent vortices more effectively. Note that 9 indicates the trajectory of the inclined vortex.

In FIG. 1, both the float body 1 and the tapered portion 3 have a circular horizontal cross section, and when the float 1 with the rudder rod 2 is thrown into the molten metal/slag interface and suspended, the rudder rod The movable area at the molten metal/slag interface at the center of the float 1 with
is equal to the diameter Dt of the widest part of the tapered portion 3. In order to prevent all the vortices that may be generated by the float 1 with the rudder 2, the diameter Df of the float body 1 at the molten metal 6/slag 7 interface must be sufficiently large relative to the diameter d of the pouring port. In addition, the movable area of the float 1 with the rudder rod 2 only needs to cover the spread of the vortex generation area that depends on the diameter d of the pouring spout, and for this purpose, Equations 1 and 5 only need to be satisfied.

1.5d<Df
...(Math. 1) 2.5d<Dt
...(Equation 5) Also, in order for the float 1 with the rudder 2 to respond to all the vortices that may occur and move itself to the center of its rotational force, the movable area at the center of the float 1 with the rudder 2 must be It is only necessary to prevent it from deviating from the vicinity of the vortex generation region which depends on the aperture d, and for this purpose, it is sufficient to satisfy Equation 6.

[0013] Dt <12d
...(Math. 6) Combining Equation 5 and Equation 6 yields Equation 2. 2.5d<Dt<12d
...(Math. 2) Also, the rudder rod 2 at the end of pouring
The introduction of the float 1 with the attached float 1 must be carried out so that the float 1 does not come off the tapered portion 3 and so that the vortex 8 is not generated before the float 1 is introduced.

In order to prevent the float from coming off the tapered shape, first, the position of the rudder rod 2, that is, the horizontal deviation of the center of the float 1 from the center of the pouring spout 4, must be adjusted to the maximum width of the taper shape at the bottom of the container. It must be within a range smaller than the diameter Dt of the portion, that is, it must satisfy Equation 3 as described above. 2ri <Dt
...(Math. 3) Next, if the lower end of the rudder rod 2 of the float 1 with rudder rod 2 comes to a lower position than the widest part of the taper-shaped part 3, or if it comes to a higher position, the distance in the height direction between them is It is necessary to input it so that it is as small as possible, and for this purpose, it is sufficient to satisfy Equation 7.

hi <ht +2(hf +lf)
...(Equation 7) Also, in order to prevent vortices from occurring before the float is introduced, the distance h from the pouring port 4 to the molten metal/slag interface must be
The float may be introduced when i is larger than the distance hi from the pouring spout to the interface when a vortex is generated, which depends on the diameter d of the pouring spout, and for this purpose, Equation 8 should be satisfied.

2d<hi
...(Equation 8) Equation 4 is obtained by combining Equation 7 and Equation 8. 2d<hi<ht+2(hf+lf)...(
Equation 4) By introducing the float in this manner and satisfying Equations 1 to 4, it is possible to prevent the generation of vortices and prevent the slag from flowing out during pouring.

Furthermore, by making the diameter of the lower end of the float main body smaller than the diameter Dt of the widest part of the tapered shape and the diameter df of the float rudder rod smaller than the diameter d of the pouring port, the final pouring time can be improved. At this stage, as shown in FIGS. 3(a) and 3(b), a plug is formed by the outer surface of the float body and the inner surface of the tapered portion, and pouring can be automatically completed.

Next, the present invention will be explained in more detail based on examples.

[0019]

Embodiment FIG. 4 shows an embodiment of the present invention. This is a diagram showing the relationship between the height hi of the molten metal/slag interface from the spout when the float is introduced and the vortex generation frequency fv, based on the results of observation from above inside the actual ladle. fv0 is the frequency of vortex generation when no vortex preventer is used.

In this embodiment, the same bottom shape (d=
A ladle with a diameter of 100 mm, Dt = 2.5 d, ht = 3 d) was used. The float used was the rudder rod float of the present invention (hf = 0.5d, lf = 3d).
, rudderless float (hf = 0.5d) and rudderless suspended support float (hf = 0.5d). The shape of each float body was the same as that shown in FIG. 1, and Df = 1.5d.

[0021] The pouring rate was 6 ton/min. Then, each float was placed in an area that satisfies the equation 3. 2ri <Dt
...(Math. 3) When a float with a rudder was used, almost no vortex was generated when it was introduced at hi satisfying Equation 4.

2d<hi<ht+2(hf+lf)...(
Equation 4) On the other hand, when hi < 2d, the frequency of vortices occurring before the injection increases, and hi > ht + 2 (h
f+lf), the frequency with which the rudder-attached float came off the tapered portion of the bottom of the ladle increased. When a float without a rudder rod was used, fv /fv0 showed a low value when inputting at hi satisfying Equation 9, but it was a higher value than when the float with a rudder rod was used. This indicates that the rudder rod has a function of automatically controlling the position of the float itself to a position where vortex generation is desired to begin. When inputting at hi <2d, the frequency of vortex generation increases before inputting, and hi >ht +2hf
When the ladle was poured into the ladle, the frequency with which the float came off the tapered part at the bottom of the ladle increased.

2d<hi<ht+2hf
...(Equation 9) Here, it can be seen that the advantage of having a rudder increases as the length of the rudder increases. When using a suspended support float without a rudder, fv at 2d<hi
/fv0 remained constant, but this value was clearly higher than when using a float with a rudder without suspension support and a float without a rudder under the conditions of Equation 4 and Equation 9, respectively. there were.

The reason for this is that the upward tension applied to the float inhibits the float from moving toward the center of rotational force at the vortex generation location. Further, FIG. 5 shows another embodiment of the present invention. This is a diagram showing the relationship between the diameter Dt of the widest part of the tapered shape at the bottom of the ladle and the frequency of vortex generation fv, based on the results of observation from above inside the actual ladle.

[0025] In each implementation, pouring port diameter d = 100 m
m, tapered part dimensions ht = 3d, Dt = 1.5d
A ~26d ladle was used. Pouring speed is 6 ton/mi
It was n. The dimensions of the float with rudder used are D
f = 1.5d, hf = 0.5d, lf = 3d
The input range was set as ri < 1.2d, and the input timing was set as hi = ht + hf + lf.

[0026] As a result of this implementation, almost no vortices were generated within the range satisfying Equation 2. 2.5d<Dt<12d
...(Number 2)

[0027]

[Effects of the Invention] In the present invention, the periphery of the pouring port provided at the bottom of the holding container is tapered in the height direction so that the upper part is wider and the lower part is narrower. Before the vortex toward the spout is generated, a float consisting of a body and a rudder extending downward from its center is
The float was made to float freely so that the lower tip of the rudder rod was located inside the tapered section and the float body was located at the interface between the molten metal and the slag existing on its surface. Since it floats and prevents the generation of vortices, and its position is stable near the pouring spout, it is now possible to more effectively prevent all vortices, including inclined vortices.

Furthermore, since the diameter of the lower end of the float body is made smaller than the diameter of the widest part of the tapered shape, and the diameter of the float rudder is made smaller than the diameter of the pouring spout, the float body A plug is formed by the outer surface of the taper and the inner surface of the tapered part, and pouring can now be finished automatically.

[Brief explanation of drawings]

FIG. 1 is a side view showing an example of the shape of a float with a rudder according to the present invention and the tapered shape of the bottom of the container.

FIG. 2 is a side view showing how tilted vortices are prevented by the rudder-equipped float of the present invention.

FIG. 3 is a side view showing two examples of the automatic pouring termination method according to the present invention.

FIG. 4 is a graph showing the relationship between the input timing of the rudder-equipped float and the frequency of vortex generation in the present invention.

FIG. 5 is a graph showing the relationship between the diameter of the widest part of the tapered bottom portion of the container and the frequency of vortex generation in the present invention.

[Explanation of symbols]

1 Float body 2　Rudder pin 3　Tapered part 4 Pouring spout 5 Bottom of container 6 Molten metal 7 Slag 8. Vortex in the early stages of generation 9 Trajectory of inclined vortices

Claims (2)

[Claims] Claim 1: When discharging and pouring molten metal from a holding container into another container, a pouring hole with a diameter d is provided at the bottom of the holding container, and the periphery of the pouring hole is widened in the height direction so that the maximum diameter Dt and height ht, a float consisting of a main body and a rudder rod extending downward from the center is placed in the molten metal in the holding container at the end of pouring. A method for preventing slag from flowing out from a molten metal holding container, characterized by charging the slag under conditions that satisfy the following. 1.5d<Df
...(Math. 1) 2.5d<Dt<12d
...(Math 2) 2ri
<Dt...(Math. 3) 2d<hi <ht +2(hf +lf)
...(Equation 4) However, Df: Diameter of the cross section of the float body at the interface between the molten metal and slag hf: Vertical distance between the lower end of the float body and the molten metal/slag interface lf: Length ri of the float rudder bar : Distance in the horizontal direction between the center of the float and the center of the pouring spout when the float is introduced. Hi: Distance in the vertical direction between the molten metal/slag interface and the pouring spout when the float is introduced. 2. The diameter of the lower end of the float body is smaller than the maximum diameter Dt of the tapered part, and the diameter df of the float rudder is smaller than the diameter d of the pouring spout, so that in the final stage of pouring, the float body 2. The method for preventing slag outflow from a molten metal holding container according to claim 1, wherein the outer surface of the molten metal holding container and the inner surface of the tapered portion form a plug to automatically terminate pouring.