JPH0227061B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to the structure of a tundish for horizontal continuous casting in which a heating device is provided on the side wall of a vertical cylindrical tundish body.

(Prior art and its problems) A conventional vertical cylindrical tundish for horizontal continuous casting has a structure in which the axis of the mold is disposed at the bottom of the tundish body at a substantially right angle to the axis of the body (for example, (Refer to Japanese Patent Publication No. 57-209752) Therefore, when an induction heating device (induction coil) is provided in a tundish having this structure, the non-heated area in the lower part of the tundish becomes wider due to the relationship with the mold. For this reason, the amount of molten steel to be induction heated is generally small, making it difficult to control the temperature of the molten steel, and the power capacity of the induction coil needs to be increased, which is uneconomical. This tendency becomes especially noticeable when the slab size is large, or in other words, when the mold becomes large.Also, at the end of casting, when the molten steel level in the tundish has decreased, most of the molten steel is no longer heated, so temperature control is necessary. was even more difficult.

Moreover, in the above-mentioned structure, since the necessary static pressure of molten steel cannot be secured until the final stage of casting, molten steel remains in the tundish, resulting in a correspondingly lower yield.

Furthermore, recently, a structure as shown in Fig. 7 in which the body of the tandate is tilted sideways has been developed (Japanese Patent Laid-Open Publication No.
58-125345), but in this structure, when molten steel is poured into the tundish from the ladle or melting furnace, the pouring column hits the inside of the induction coil 2 on the inside wall of the main body 1. There is a risk that the refractory material will be damaged, and the structure of the tundish body 1 becomes complicated.

Furthermore, in the tundish structure disclosed in JP-A No. 58-145336, the housing of the tundish nozzle part is formed of an integral structure, so that the tundish nozzle has particularly strict control over erosion. It was difficult to inspect and repair the area.

In addition, any of the above-mentioned conventional techniques or Japanese Patent Application Laid-open No.
In the tundish structure described in Japanese Patent No. 59-42159, a conduit communicating with the bottom of the tundish body is provided in the mold substantially horizontally at substantially the same level as the bottom surface of the tundish body. Therefore,
It is not possible to apply static pressure to the molten steel in the mold until the molten steel in the tundish is completely exhausted.
In other words, when the molten steel level drops, the feeder action disappears and the molten steel remains at the bottom of the tundish, which is disadvantageous. If this happens, the yield will be poor, and the molten steel remaining in the tundish will damage the refractories in the tundish after casting is finished, which is a disadvantage.

In addition, as a conventional technique for horizontal continuous casting, there is a method in which the tundish and mold are integrated and horizontally vibrated (reciprocating motion), and the slab is pulled out at a constant speed. The problem was that the equipment became larger.

(Object of the Invention) Therefore, in view of the above-mentioned points, the present invention provides a method in which a substantially L-shaped runner conduit is introduced below the bottom level of the tundish in a route from the bottom of the tundish main body to the tundish nozzle. Due to this, etc.
Static pressure of molten steel is constantly applied inside the mold to enable efficient casting, and the mold is always held horizontally and has a structure that allows it to vibrate back and forth horizontally (reciprocating movement) to improve the quality of slabs and facilitate smooth drawing. The purpose is to

(Means for Solving the Problems) Therefore, the gist of the present invention is to provide a heating device on the side wall of a vertical cylindrical tundish main body with an open top end in a tundish for horizontal continuous casting in which the tundish and the mold are sealed and continuous. , a substantially L-shaped runner conduit formed separately from the tundish body and formed by a vertical portion and a horizontal portion is introduced downward from the bottom of the tundish body in a path leading from the bottom of the tundish body to the tundish nozzle; At the same time, the inner diameter of at least the horizontal portion of this L-shaped runner pipe is greatly reduced compared to the cross-sectional area of the tundish main body, and the inner diameter of the mold is approximately 3.5 mm.
At the same time, a slidable on-off valve is provided at the runner opening on the bottom of the tundish, the tundish nozzle is connected to the front end of the mold, and the mold is mounted on a trolley capable of reciprocating vibration. The mold is pivotably supported on the support device above, and a horizontal holding device is provided to compensate for the weight of the mold and hold the mold horizontally, so that it can vibrate horizontally while always holding the mold horizontally. A tundish for horizontal continuous casting is characterized in that it is configured as follows.

(Function) By vibrating the mold back and forth while the mold is always held horizontally by the horizontal holding device, the slab can be pulled out more smoothly and the surface quality can be improved. Further, by introducing an L-shaped runner conduit below the bottom of the tundish body, static pressure of molten steel can be applied within the mold until the molten steel in the tundish is exhausted.
In other words, a feeder action is obtained within the mold until the end of casting. Additionally, maintenance around the tandate nozzle can be easily performed.

In addition, the amount of molten steel in the tundish main body below the heating device (non-heated area) is extremely small, and therefore the temperature drop of the molten steel near the tundish nozzle is small, making it possible to obtain stable slab quality.

(Example) Hereinafter, an example of the present invention will be described based on the drawings.

FIG. 1 shows a central sectional view of a basic tundish. In the figure, reference numeral 1 denotes a vertical cylindrical tundish body with an open upper end, and a side wall 1 of this body 1.
An induction coil 2 as a heating device is disposed around the area from the upper part to the lower part of a. Then, a substantially L-shaped runner conduit 1c consisting of a horizontal portion and a vertical portion separate from the tundish main body 1 is connected to the tundish main body 1 in a path leading to the tundish nozzle 3 communicating with the opening at the bottom of the tundish main body 1. (bottom surface) so that the horizontal part is located at a lower level. The L-shaped runner conduit 1c has the same inner diameter at its vertical portion and horizontal portion. In addition, the horizontal portion of the runner conduit 1c is significantly reduced in diameter than the tundish main body 1. The tundish nozzle 3 is arranged on the outer wall surface of the side wall 1a of the main body 1. Therefore, when a mold (not shown) is communicated with the tundish nozzle 3, the side wall 1a does not become an obstacle, and the size and shape of the mold are not restricted. Moreover, the housing 3' of the tundish nozzle 3 parts, that is, the L-shaped runner 1c
The structure is such that the nozzle housing 3' can be freely removed from the main body 1 by forming flanges 1b on the outer shells of the main body 1 and the nozzle housing 3'. Therefore, the tundish nozzle 3 can be replaced and the refractory material near the nozzle 3 can be easily inspected and repaired. In addition, in the figure, 5
are the molten steel inlet A and B above the tundish body 1.
is a slab.

As mentioned above, there is approximately L in the path leading to the tundish dish 3 that communicates with the opening at the bottom of the tundish body 1.
By protruding the letter-shaped runner pipe 1c, it becomes possible to apply static pressure to the molten steel in the mold until the molten steel in the tundish body 1 is exhausted, and casting can be performed without leaving any molten steel in the tundish body 1. Furthermore, since no molten steel remains, the refractories within the tundish body 1 will not be damaged after casting is completed.

On the other hand, in the tundish main body 1, a valve seat 6 is disposed in the runner opening 1d on the bottom surface, and the upper end of the valve stem 7 whose lower end can be joined to the valve seat 6 is supported by an L-shaped support member 8. Suspended so that it can move up and down. Further, the vertical portion 8a of the support member 8 is attached to the outer wall of the tundish main body 1 so as to be movable up and down with a support fitting 9, and a part of the vertical portion 8a is attached to the rack 8b.
A pinion 1 is formed to mesh with this rack 8b.
A control lever 10 having an end portion 0a is pivotally mounted, and the lever 10 controls the movement of the valve stem 7 toward and away from the valve seat 6.
This should be done by Therefore, the runner opening 1d can be closed until the molten steel is poured into the tundish and the temperature of the molten steel is stabilized, making it possible to cast at an optimal temperature.

Further, the induction coil 2 is connected to an upper part 2a and a lower part 2b.
It is divided into two parts so that power can be supplied and controlled individually to each coil 2a and 2b. Therefore, it is possible to supply power commensurate with the temperature distribution of the molten steel in the tundish, and also to supply power commensurate with the amount of molten steel remaining in the tundish just before the end of casting (for example, when the level of molten steel in the tundish has decreased). Efficient heating becomes possible.
Furthermore, a bubbling gas supply plug 11 is provided on the bottom of the tundish main body 1, and a gas supply pipe 12 is provided.
The temperature of the molten steel in the tundish is equalized by connecting the tundish.

FIG. 2 is an overall front view of a tundish having the basic configuration shown in FIG. 1 above. In the figure, a tundish body 1 is equipped with a horizontally slidable on-off valve 13 in the runner opening 1d on the bottom, a hydraulic cylinder 14 pivotally mounted on the outer wall of the body 1, and a bell pivotally mounted below the hydraulic cylinder 14. The on-off valve 13 is configured to be opened and closed via a crank 15 and a connecting rod 16. Then, in the lower part of the tundish body 1, an L-shaped runner conduit 1c whose vertical portion and horizontal portion have the same inner diameter as described above is provided.
It is introduced by Further, the middle position of the mold 4 is pivotally supported by a supporting device 17 so as to be able to swing freely, and horizontal holding devices 18 are provided at both ends of the mold 4 to correct the weight and hold the mold 4 horizontally. Then, the tandate nozzle 3 at the end of the pipe 1c is connected to the front end of the mold 4, and is connected to the upper end of the pipe 1c via a hydraulic cylinder 19 whose one end is pivotally connected to the bottom end of the main body 1 and a connecting bracket 20. The opening can be press-fitted to the runner opening 1d on the main body 1 side. Therefore, with this structure, the pouring and stopping of molten steel can be controlled, and the L-shaped runner pipe 1c and the mold 4 can be easily replaced.

FIG. 3 shows a second embodiment, in which the L-shaped runner pipe 1c and the mold 4 of the first embodiment are connected to the track 2.
1 is mounted on a movable trolley 22. That is, the mold 4 is horizontally held by the horizontal holding device 18.
It is configured to be able to reciprocate in the drawing direction of the slab B, that is, to be able to vibrate horizontally, while being held horizontally at all times. As a result, the slab B can be pulled out more smoothly, and its quality is also improved. Furthermore, the mold 4 can be conveniently moved by the trolley 22 when the mold 4 is replaced. Note that the cart 22 is fixed to the track 21 during casting work. In the figure, 23 corresponds to the hydraulic cylinder 19.

FIG. 4 shows a third embodiment, in which, in the second embodiment, the reciprocating movement (that is, including horizontal vibration) of the truck 22 and the opening/closing operation of the on-off valve 13 can be performed by a common hydraulic cylinder 24. That is, in order to vibrate (reciprocate) only the mold 4, a simple and small hydraulic cylinder 24 is employed as its driving device. The on-off valve 13 is attached to the upper end of the L-shaped runner pipe 1c. In addition, trolley 2
The movement range of 2 is restricted by the relationship with the opening/closing operation of the on-off valve 13.

Next, conditions for determining the size of each runner pipe (route) 1c in the embodiment of the present invention will be explained. Note that although the runners and slabs are not particularly limited to circular cross-sections, conditions are determined when they are circular.

1 Maximum diameter of runner pipe In Fig. 5, D: inner diameter of the pipe, d: inner diameter of the mold, V: drawing speed of slab, and L: length of the pipe.

The temperature drop rate t of molten steel in the non-heated region is usually 2 to 3°C/min, but the temperature drop s of molten steel
must be controlled within a range of 10℃, so the following conditions must be met.

π/4×D ² ×L≦π/4×d ² ×V×(s/t) ∴D≦[V×(s/t)/L] ^1/2 ×d Here, L is 0.5 due to the structure ~1.0m,
V is generally about 1.0 to 3.0 m/min, so if L = 0.75 m, V = 2.0 m/min, t = 2.5°C/min, and s = 10°C, then D≦3.3×d Therefore, the runner The maximum diameter of the channel is approximately 3.5 times the inner diameter of the mold.

2 Minimum diameter of runner pipe In Fig. 6, D: inner diameter of the pipe, d: inner diameter of the mold, V: drawing speed of slab, and U: flow rate of molten steel in the pipe.

The molten steel flow in the runner pipe is a laminar region that helps impurities float to the surface, reduces frictional force with the runner pipe, reduces wear on the refractory, and flows into the mold in a laminar state. It is necessary to make the coagulation uniform within. To satisfy the above conditions, the following steps should be taken.

From the condition of Raynozzle number for laminar flow of molten steel, Re=UD/ν≦Rec ν: Kinematic viscosity coefficient of molten steel (1×10 ^-6 m ² /sec), Re: Raynozzle number of molten steel, Rec: Criticality Ray nozzle number (3000) On the other hand, the following formula holds for the inflow amount of molten steel.

π/4×D ² ×U=π/4×d ² ×V From the previous equation, since U=Re×ν/D, D×Re×ν=d ² ×V ∴Re=d ² ×V/ (D×ν) According to the condition of Re≦Rec, D≧d ² ×V/(Rec×ν) When V=2.0m/min=0.033m/sec, when d=100mm=0.1m, D≧0.11m= 110mm Therefore, the minimum diameter of the runner pipe is approximately the inner diameter of the mold.

(Effects of the Invention) As explained above, according to the present invention, since the mold is always held horizontally by the horizontal holding device and can vibrate back and forth, the continuous drawing of slabs is made smoother. , the remarkable effect of improving the quality (especially the surface quality of the slab) can be obtained. In addition, since the reciprocating vibration only occurs in the mold, the reciprocating (vibration) device can be configured with a hydraulic cylinder, etc., and the device can be simple and small. accompany.

(1) Since the L-shaped runner conduit is installed below the level of the bottom of the tundish from the lower part of the tundish to the tundish nozzle, the molten steel is kept in the mold until the molten steel in the tundish is exhausted. Static pressure can be applied, reducing the amount of hot water remaining in the tundish tank.
Yield can be improved.

In addition, since the static pressure of the molten steel remains high until the end, creating a feeder effect within the mold, it is possible to maintain a large contact between the solidified shell and the mold within the mold, resulting in good quality while maintaining a high casting speed. It is possible to obtain beautiful slabs.

Furthermore, since no molten steel remains in the tundish, the refractories in the tundish will not be damaged after casting is completed.

Furthermore, there is little variation in the molten steel level in response to changes in the amount of molten steel in the tundish, and the heating effect by the heating device is sufficient even when the molten steel level decreases. In addition, by setting the runner path in the non-heating area to 3.5 times or less the inner diameter of the mold, the amount of molten steel in the non-heating area is reduced, reducing the temperature drop near the nozzle and obtaining stable slabs of high quality. Can be done.

(2) Since the induction heating coil is provided on the side wall of the tundish body, the heating device can be easily placed in the tundish without affecting the size of the mold or the method of attaching it.

(3) Since the L-shaped runner pipe is formed separately from the tundish body, maintenance such as inspection and repair around the tundish nozzle, where erosion control is particularly strict, can be performed easily and in a short time. obtain.

[Brief explanation of drawings]

1 to 6 are explanatory diagrams of embodiments of the present invention, in which FIG. 1 is a central vertical sectional view of a tundish, and FIG. 2 is a tundish that shows a first embodiment having the basic configuration of FIG. 1. Overall front view of nearby area, 3rd
The figure is an overall front view showing the second embodiment, FIG. 4 is an overall front view showing the third embodiment, and FIGS.
The figure is an explanatory diagram of the same outline. FIG. 7 is a central longitudinal sectional view showing a conventional inclined tundish. 1... Tanditetsu main body, 1a... Side wall, 1
b, ... flange, 1c ... runner route (pipe line),
2... Heating device (induction coil), 3... Tundish nozzle, 3'... Nozzle housing, 4...
...Mold, 17... Support device, 18... Horizontal holding device, 22... Dolly, 24... Hydraulic cylinder.

Claims (1)

[Claims] 1. In a tundish for horizontal continuous casting in which the tundish and the mold are sealed and continuous, a heating device is provided on the side wall of a vertical cylindrical tundish main body with an open top end, and the tundish is installed in a path from the bottom of the tundish main body to the tundish nozzle. A substantially L-shaped runner conduit formed separately from the main body by a vertical portion and a horizontal portion is led downward from the bottom of the tundish, and the inner diameter of at least the horizontal portion of this L-shaped runner conduit is The diameter of the tundish is significantly reduced compared to the cross-sectional area of the tundish body, and is set to approximately 3.5 times or less the inner diameter of the mold, while a slidable on-off valve is installed in the runner opening on the bottom of the tundish. The tandate nozzle portion is coupled to the front end of the mold, and the mold is pivotably supported on a support device on a trolley capable of reciprocating vibration, and the weight of the mold is compensated for to keep the mold horizontal. 1. A tundish for horizontal continuous casting, characterized in that the tundish is equipped with a horizontal holding device for holding the mold horizontally, and is configured to be able to reciprocate and vibrate while always holding the mold horizontally.