JP2680470B2 - Belt cooling method of twin belt type continuous casting machine - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for cooling a belt with cooling water in a twin-belt type continuous casting machine used for continuous casting of thin plates.

[Conventional technology]

2. Description of the Related Art A twin-belt continuous casting machine has been conventionally used which forms a casting space in the wall thickness direction of a thin plate to be cast by a pair of belts and continuously supplies molten metal from a pouring nozzle to perform continuous casting. An example of this continuous casting machine is disclosed in Japanese Patent Laid-Open No. 60-152347, and its outline is shown in FIG.

A pair of metal belts 50, 51 drive pulleys 52,
A casting space is formed between the belts 50 and 51 which are wound around the 53 and the pulley 54 and pass in a substantially vertical direction. A cooling pad 55 for cooling the back surfaces of the belts 50, 51 with cooling water is provided in a portion corresponding to the casting space, and the fin pad 56 for receiving and supporting the back surfaces of the belts 50, 51 is provided on the cooling pad 55. Are arranged. Further, in order to solidify the supplied molten metal, a cooling nozzle 57 for spraying cooling water to the belts 50, 51 to cool the belt is provided in the pulley 54 portion. Then, the pouring nozzle 58 is inserted into the upper end of the casting space,
The supplied molten metal becomes a thin slab A between the belts 50 and 51 and is discharged downstream.

The cooling pad 55 is in the form of a closed container, and in the illustrated example, it is configured as having two chambers 55a and 55b at the top and bottom. As shown in FIG. 4, these chambers 55a and 55b are divided by a partition wall 55c, each of which has a vertical partition wall 5 having a gap between the surfaces facing the belts 50 and 51.
It has 5d and 55e. Then, the partition wall 55c is abutted against the surfaces of the belts 50 and 51, and the space between the partition wall 55c and the vertical partition walls 55d and 55e formed at this time serves as a cooling water flow path. On the other hand, the cooling water is supplied from an external water supply source and flows into the belts 50, 51 from the lower ends of the vertical partition walls 55d, 55e as indicated by arrows in the figure. During this time belt 50,
After cooling 51, it returns to the chambers 55a and 55b from the upper end and is discharged to the outside, and this circulation is repeated.

FIG. 5 is a schematic diagram showing a cooling pad 55 and a cooling water circulation system. In the illustrated example, the chamber 55f of one stage is further provided in the two-stage system of FIG. Then, a supply pipe 59a and a discharge pipe 59b of cooling water are connected to the chamber 55a to supply cooling water between the vertical partition wall 55d and the surfaces of the belts 50 and 51. These cooling water circulation pipes are connected to each of the chambers 55a, 55b, 55f.

[Problems to be solved by the invention]

When performing continuous casting using the belts 50 and 51, the meniscus portion a having a low molten metal static pressure shows the water pressure of the cooling water injected from the cooling nozzle 57 and the lower side having a high molten metal static pressure shows the water pressure of the cooling water in the cooling pad 55. Utilizing this, the molten metal or slab and the belts 50, 51 are balanced. FIG. 6 is a diagram showing the relationship between the internal pressure P ₁ due to the cooling water in the cooling pad 55 and the static pressure P ₂ of the molten metal and the slab, where the horizontal axis is the pressure and the vertical axis is the height of the molten metal and the cooling pad 55. Indicates. In the figure (a), the internal pressure P ₁ in the cooling pad 55 is the static pressure.
It is smaller than P ₂ , and the belts 50 and 51 do not bulge toward the casting space side as shown by the solid line in FIG. On the other hand, when the internal pressure P ₁ is larger than the static pressure P ₂ of the molten metal and the cast piece as shown in FIG. 7B, the belts 50 and 51 are bulged and deformed as shown by the broken lines.
Therefore, deformation of the belts 50 and 51 does not occur as long as the internal pressure P ₁ and the static pressure P _{2 of} the cooling pad 55 are adjusted.

As a result of the investigation, it was found that in the belt type continuous casting machine, the force for pushing the belts 50 and 51 toward the casting space side is generated by the following.

(1) The jet flow of the cooling water from the cooling nozzle 57 bends in the direction of 90 ° toward the outside at the partition point with the cooling pad 55 to generate a reaction force, and this reaction force causes the belt 50, 51
Is extruded.

(2) In the case of only the cooling pad 55, when the belts 50, 51 are slightly exposed to the casting space side, the flow path of the cooling pad 55 is expanded and cooling water is likely to flow upward. Therefore, the internal pressure of the cooling pad 55 decreases, and the extrusion of the belts 50 and 51 does not proceed.
However, when the jet flow of cooling water from the cooling nozzle 57 hits the upper portions of the belts 50 and 51, the impact pressure causes the cooling pad 5 to
The internal pressure of 5 rises and push-out force is generated.

On the other hand, in the actual operation, the cooling water is continuously jetted from the cooling nozzle 57 even after the casting is completed, and the cooling water is still flowing in the cooling pad 55. This is because the slab is cooled and solidified, and if the cooling water is stopped, the belt 50, 51
This is to prevent this because melting loss occurs.

In this way, when cooling water is supplied even after casting,
A phenomenon occurs in which the belts 50 and 51 are extruded toward the casting space. On the other hand, when the upper end of the slab is pulled out at the end of casting, the static pressure decreases, so that the belts 50 and 51 are pushed out for the reason described above. Therefore, the belts 50 and 51 are connected to the pouring nozzle 58.
It is easy for the belts 50 and 51 to be deformed by being pressed against the short side block provided between the belts 50 and 51 and being strongly pressed.

The problem to be solved in the present invention is to prevent the belt from being pushed out due to the water pressure of the cooling water generated at the end of casting, thereby preventing the deformation of the belt.

[Means for solving the problem]

According to the present invention, a pair of belts that create a casting space in a substantially vertical direction around a pair of pulleys that are provided at intervals, and a belt that melts and runs away from the peripheral surface of the pulley are cooled on the back surface of the molten metal injection portion. Twin-belt type having a cooling nozzle for injecting water, and a plurality of chambers having cooling pads arranged sequentially from the upper side to the lower side downstream of the cooling nozzle and cooling the cooling water by contacting the belt with the cooling water In the belt cooling method of the continuous casting machine, the injection of the cooling water from the cooling nozzle is stopped in accordance with the stop of the molten metal into the casting space at the end of casting, and then the upper end of the slab descending between the belts. The supply of the cooling water to each of the chambers is sequentially stopped in accordance with the movement.

[Action]

When the pouring is stopped at the end of casting, the injection of the cooling water from the cooling nozzle is also stopped, and the force that pushes the belt to the casting space side does not act on the belt that has no load due to the descent of the molten metal. Also, when the molten metal solidifies and gradually becomes a slab and descends, the water pressure of the cooling water on the cooling pad decreases,
The force with which the cooling water presses the belt also decreases according to the load that the belt receives from the slab. For this reason, the pressure of the cooling water can be changed according to the load from the casting space side of the belt that changes according to the movement of the slab, and the slab can be removed while suppressing the force for pushing the belt.

〔Example〕

 FIG. 1 is a schematic view showing a main part of the present invention.

In the figure, as in the conventional example, a pair of belts 1 and 2 are respectively wound around drive pulleys 3a and 3b and pulleys 4a and 4b, and the belts 1 and 2 travel in the direction of the arrow by the operation of the drive pulleys 3a and 3b. The pouring nozzle 5 is inserted from the upper end portion between the belts 1 and 2, and the molten metal injected from this is gradually solidified from the meniscus portion a and is drawn out as a cast piece A. Further, the cooling nozzles 6 and 7 are installed by the pipes provided around the pulleys 4a and 4b so that the cooling water can be sprayed over substantially the entire lengths of the belts 1 and 2 in the width direction. Then, the cooling water from the cooling nozzles 6 and 7 is jetted according to the level of the meniscus portion a of the belts 1 and 2, and the belts 1 and 2 are balanced by balancing the cooling water pressure with the static pressure of the meniscus portion a. Prevents swelling on the melt side.

Cooling pad 8, provided to further solidify the molten metal,
9 are arranged along the pass surfaces of belts 1 and 2, respectively. The cooling pad 8 on the left side has three chambers 8a, 8b,
Each chamber 8a-8c is provided with a partition 8d and a vertical partition 8e. Further, the cooling pad 9 on the right side has the same structure, and the partition 8d and the vertical partition are provided in the three-stage chambers 9a, 9b, 9c.
9e.

A supply pipe 10 and a discharge pipe 11 of cooling water are connected to each chamber 8a of the cooling pad 8 on the left side, and the supplied cooling water passes between the vertical partition wall 8e and the surface of the belt 1 in the chamber 8a. Then, the belt 1 is cooled. A pressure reducing valve 10a, a shutoff valve 10b, and a flow rate adjusting valve 10c are incorporated in the supply pipe 10, and a manual on-off valve 11a is provided in the discharge pipe 11. These supply pipe 10, discharge pipe 11 and various valves are provided in the other chamber 8
Similarly, the cooling pads 9 on the right side have the same cooling water circulation system.

In the above configuration, when the molten metal is supplied from the pouring nozzle 5, the cooling water is jetted from the cooling water nozzles 6 and 7 to the back surfaces of the belts 1 and 2. On the other hand, the cooling water is also circulated and supplied to the cooling pads 8 and 9 to cool the molten metal and send it out as a slab A.

When the injection of the molten metal from the pouring nozzle 5 is completed and the molten metal stops, the ejection of the cooling water from the cooling nozzles 6 and 7 is stopped. Thereafter, the slab A gradually cooled by the cooling pads 8 and 9 is drawn out between the belts 1 and 2, so that the level of the upper end of the slab A also gradually decreases. Then, in accordance with the movement of the slab A, the supply of the cooling water to the chambers 8a to 9c of the cooling pads 8 and 9 is sequentially stopped. The cooling water is stopped in each of the chambers 8a to 9c at approximately the same time as or immediately after the passage of the slab A in each chamber. That is, the cooling nozzle
After the cooling water from 6, 7 is stopped, while the cast slab A descends and the upper end thereof passes through the uppermost chambers 8a, 9a, the cooling water is continuously supplied to all the chambers 8a-9c. Supply. When the upper end of the slab A passes through the chambers 8a and 9a, the cooling water to these chambers 8a and 9a is stopped by the shutoff valve 10b, and the cooling water is continuously supplied to the middle and lower chambers 8b to 9c. It After this, when the cast slab A exits the middle chambers 8b and 9b, the cooling water to these chambers 8b and 9b is stopped, and when the cast slab A exits the lower chambers 8c and 9c, these The cooling water to the chambers 8c and 9c is also stopped.

Thus, when the injection of the molten metal is stopped at the end of casting, the cooling water is no longer jetted from the cooling nozzles 6 and 7, and the cooling water to the chambers 8a to 9c is sequentially moved as the cast slab A moves. Stop. Therefore, when the pressure of the molten metal supplied between the belts 1 and 2 is exhausted, the cooling water injection pressure of the cooling nozzles 6 and 7 also becomes zero, and the belts 1 and 2 are pushed out toward the pouring nozzle 5 side. Never. Also cooling pad
The water pressure load by 8 and 9 is 8 in each of the upper, middle and lower chambers.
Since the load of the pushing force on the belts 1 and 2 gradually decreases in units of a to 9c, the belts 1 and 2 do not bulge and deform in the same manner.

In addition, in the case where the cooling water is still flowing as in the conventional case,
The overhang of the belts 1 and 2 was about half of the casting thickness, and the belts 1 and 2 were in close contact with each other. Further, according to the measurement of permanent deformation after the completion of casting, the maximum deformation (waviness) of the belts 1 and 2 was about 10 mm. On the other hand, in the example of FIG. 1, the protruding amount of the belts 1 and 2 is 5 mm or less when the withdrawal length of the slab A is 1/2 mold length or more, and 5 to 10 mm when it is 1/2 mold length or more. And the permanent deformation was 5 mm or less.

FIG. 2 is a schematic diagram showing a second embodiment, in which the flow rate and pressure of the cooling water supplied to the chambers 8a to 9c are controlled.

In the figure, the supply pipe 10 is provided with a flow control valve 12,
A pressure control valve 13 is incorporated in the discharge pipe 11. The flow rate control valve 12 sets the flow rate of the cooling water to each of the chambers 8a to 9c, and the belts 1 and 2 are used when the cast slab A goes out.
Since the area heated by is gradually reduced, the flow rate is set by the flow rate control valve 12 accordingly. The belt
It has already been confirmed that the amount of water required for cooling 1 and 2 should be about 1/3 in the casting process. Also, the pressure control valve
Reference numeral 13 controls the pressure of the cooling water passing through the chambers 8a to 9c. When the slab A comes out, the area of the slab passing through each of the chambers 8a to 9c in contact with the cooling water gradually decreases, so that the load received from the slab A also gradually decreases. Therefore, if the pressure of the cooling water is kept at the pressure of the cooling water when the slab A corresponds to the entire area of the chambers 8a to 9c, the pressure of the cooling water is better when the slab A is being removed. It becomes larger and pushes out belts 1 and 2. Therefore, if the pressure of the cooling water is adjusted by the pressure control valve 13 according to the falling of the cast slab A, the generation of the pushing force to the belts 1 and 2 can be suppressed. The flow rate control valve 12 and the pressure control valve 13 are included in the control system of the sequencer 14, and are controlled by giving flow rate target values and pressure target values for the chambers 8a to 9c.

Also in this example, the cooling nozzle 6,
Stopping the injection of cooling water from 7 is the same as in the case of FIG. While the cast slab A is passing through the cooling pads 8 and 9, the chambers 8a to 9c corresponding to the position of the cast slab A are removed.
The supply amount and pressure of the cooling water to the control unit are controlled. This control is performed by the flow rate control valve 12 and the pressure control valve 13 as described above, and the internal pressures of the cooling pads 8 and 9 are adjusted according to the movement of the slab A so that the belts 1 and 2 do not overhang. To do.
Therefore, the slab A can be finally removed without stopping the cooling water, and the solidification of the slab A can be promoted and the melting damage of the belts 1 and 2 can be prevented. In the example of FIG. 2, the amount of overhang of the belts 1 and 2 was 5 mm or less in the total drawing length of the slab A, and there was no permanent deformation.

〔The invention's effect〕

(1) Since the spouting of the cooling water from the cooling nozzle is stopped after the pouring of the molten metal is stopped, the belt that has no load from the molten metal is not pushed out. Therefore, it is possible to prevent the belt from coming into contact with the pouring nozzle inserted between the belts and being damaged, or being pressed against the short side block to deform the edge of the belt.

(2) Since the water pressure of the cooling water supplied to the cooling pad is reduced in accordance with the movement of the slab, the acting force in the pushing direction to the belt after the slab comes off is also reduced. For this reason,
Similar to stopping the cooling nozzle, it is possible to prevent the belt from projecting and deforming toward the casting space side, and it becomes possible to operate the belt while maintaining the proper shape during and after the passage of the cast slab.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a first embodiment of the present invention, FIG. 2 is a schematic view of a second embodiment, FIG. 3 is a schematic view of essential parts of a twin belt type continuous casting machine, and FIG. 4 is a cooling pad. FIG. 5 is a schematic vertical sectional view showing the main part of FIG. 5, FIG. 5 is a schematic view showing deformation of the belt, and FIG. 6 is a diagram showing a relationship between casting static pressure and cooling water pressure. 1,2: Belt, 3a, 3b: Drive pulley 4a, 4b: Pulley, 5: Pouring nozzle 6,7: Cooling nozzle, 8,9: Cooling pad 10: Supply pipe, 10b: Shutoff valve 11: Discharge pipe, 12: Flow control valve 13: Pressure control valve, 14: Sequencer A: Slab, a: Meniscus part

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hidetoshi Yuyama 1 Nishinosu, Oita-shi, Oita Pref. Shin-Nippon Steel Co., Ltd. Oita Works (72) Noriyuki Kanai 1 Nishinosu, Oita-shi, Oita Pref. Steel Works Co., Ltd. Oita Steel Works (72) Inventor Kanji Shozen 4-6-22 Kannon Shinmachi, Nishi-ku, Hiroshima-shi, Hiroshima Prefecture Mitsubishi Heavy Industries Ltd. Hiroshima Works (72) Inventor Koichi Hirata Kannon-shin, Nishi-ku, Hiroshima City, Hiroshima Prefecture 4-6-22 Mitsubishi Heavy Industries, Ltd. Hiroshima Works (56) Reference JP-A-1-104448 (JP, A) JP-A-60-54247 (JP, A)

Claims (1)

(57) [Claims] 1. A pair of belts that create a casting space in a substantially vertical direction by rotating a pair of spaced pulleys, and a back surface of a molten metal injection portion of the belt that runs away from the peripheral surface of the pulleys. A twin belt having a cooling nozzle for injecting cooling water and a plurality of chambers having cooling pads arranged downstream from the cooling nozzle in order from top to bottom and cooling the cooling water by contacting the cooling water with the belt. In the belt cooling method of the continuous casting machine, the injection of cooling water from the cooling nozzle is stopped in accordance with the stop of the molten metal into the casting space at the end of casting, and then the upper end of the slab descending between the belts. The method of cooling a belt of a twin-belt continuous casting machine, characterized in that the supply of cooling water to each of the chambers is sequentially stopped in accordance with the movement of the chamber.