JP2957040B2 - Twin drum type continuous casting apparatus for thin sheet and casting method therefor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a twin-drum continuous casting apparatus for continuously casting a thin plate from a molten metal, and a continuous casting method using the continuous casting apparatus. The present invention has a feature in a method of controlling rolling down at the time of start-up (start-up) of a casting apparatus.

[0002]

2. Description of the Related Art Japanese Unexamined Patent Publication No. 1-166863 discloses one conventional technique relating to a method and a device for controlling a rolling reduction of a twin drum type continuous casting apparatus for a thin plate. In this technique, when one drum is inclined with respect to the other drum and the two drums are not parallel, a thickness difference (wedge) occurs in the width direction of the slab, and the drum end face is inclined due to the inclination of the drum. Calculate the sum of the two detected values by detecting the pressing force on the bearings at both ends of one of the drums in order to prevent a gap from forming between the and the side weir and lowering the sealing performance against the molten metal. So that the value of the sum becomes a predetermined value,
Also, the positions of the bearings supporting both ends of the other drum are set so that the two drums always keep parallel to each other.
The pressure on the slab is reduced while being adjusted by a hydraulic cylinder system capable of feedback control.

[0003]

The above prior art is intended to solve the problem of continuous casting mainly in a steady state, and is not related to a rolling reduction method in a transient state such as at startup. At times, if the reduction is performed by the method of the related art, various problems occur as follows.

(1) Since a hydraulic cylinder capable of positioning is used to move one of the drums while maintaining a parallel state with respect to the other of the drums to perform a rolling reduction control, a stable and continuous casting is still performed. At start-up when not in a state, the slab forms a notch with a significantly increased thickness. When the knob passes through the narrowest gap between the pair of drums, the drum may become inoperable or the drum may damage the driving mechanism. Further, when a deviation of the shell thickness occurs in the width direction of the slab, a portion where the reduction is not applied partially occurs, cooling of the portion is delayed, and the strength of the slab is reduced in the portion. Also, even when the shell thickness changes suddenly in the casting direction, the response speed of the hydraulic cylinder is limited, so the hydraulic cylinder cannot follow the variation in the thickness of the slab, and there is a part where reduction is not applied. Again, the strength of the slab will be reduced at that location. (2) During start-up of continuous casting, the speed of the drum is low, so part of the solidified shell once formed is re-melted by receiving the heat of the molten metal supplied later, so-called "shell washing" occurs. The probability increases and the deviation of the solidified shell thickness becomes very large. (3) In the start-up method using a dummy sheet, the deviation of the solidified shell thickness is further increased due to the influence of a wire or a metal plate attached to a portion where the slab and the dummy sheet are joined. (4) Due to the above reasons, if the reduction control at startup is also performed by the reduction control method of the prior art, a low-strength part is likely to be formed at the bottom near the tip of the slab, and The tension acting when exiting the drum gap and being guided towards the coiler breaks the slabs at the weak points, not only interrupting the continuous casting operation but also wasting a great deal of time and resources. The probability of causing very troublesome troubles requiring repair work is increased.

It is an object of the present invention to provide a means for solving the problems of the prior art rolling control of a twin-drum thin sheet continuous casting apparatus at start-up and enabling a smooth transition to a steady operation state. Is a problem to be solved.

[0006]

According to the present invention, as a means for solving the above-mentioned problems, a cooling medium such as water circulating in the inside is used, and is driven to rotate in opposite directions at the same rotation speed. A pair of drums forming a pool in which the molten metal is supplied at the upper part of the gap, bearings that rotatably support both ends of shafts of the pair of drums, and a common frame that supports the bearings. A pair of hydraulic cylinders provided between the bearing and the frame respectively supporting both ends of a shaft of one of the drums and defining a position of the one drum with respect to the other drum; and A first hydraulic supply system that connects the first hydraulic supply system to the first hydraulic supply system and a hydraulic pump that supplies the hydraulic oil to the first hydraulic supply system. The present invention provides a twin-drum continuous sheet casting apparatus characterized by comprising a second hydraulic supply system having a motor, and uses the twin-drum continuous sheet casting apparatus to start casting of slabs from the time of startup. in a first step until aneurysm passes the narrowest gap between the pair of drums, by supplying pressure oil to the bottom of the intervening of the accumulator by the second hydraulic pressure supply system to the hydraulic cylinder, the one resiliently give pressure under force to the drum, after it said first step is completed, in a second step to shell washing rotational speed is increased in the drum is not generated, the second hydraulic supply system supplying high pressure hydraulic oil than in the first step under the intervention of the accumulator to the hydraulic cylinder by, than in the case of resiliently the first step on a drum of the one In the third step, which is a state of steady continuous casting after the completion of the second step, the second hydraulic supply system is switched to the first hydraulic supply system, and the second hydraulic supply system is switched to the first hydraulic supply system. A twin-drum thin plate, comprising: shutting off an accumulator, supplying adjusted pressure oil to the pair of hydraulic cylinders, and performing a pressure reduction control so that the one drum is parallel to the other drum. Provide a continuous casting method.

[0007]

The slab immediately after the start of the twin-drum thin-sheet continuous casting apparatus has an extremely thick knob on the slab. In the present invention, the range is defined as the first step, and the hydraulic cylinder and the hydraulic pump are connected to an accumulator. Connected by a second hydraulic supply system provided to supply hydraulic oil to the hydraulic cylinder under the intervention of an accumulator, and to accumulate
Since give resiliently pressure under force by the action of the motor, when the aneurysm portion of the slab to pass through the narrow gap pair of drums, opening one can readily retract the gap of the drum, the mass of the slab Let it pass without difficulty. Accordingly, the twin-drum continuous continuous casting apparatus for a thin plate is smoothly started, and the apparatus does not fail to start, and there is no danger of damaging the drum, the driving mechanism, and the like.

After the first step is completed, the first step is also performed in the second step until the shell washing does not occur .
Similarly to Step, the hydraulic oil is supplied to the hydraulic cylinder under the intervention of the accumulator by the second hydraulic supply system. In this step, the effective hydraulic pressure acting on the hydraulic cylinder is supplied to the first hydraulic cylinder.
Since a high pressure than in the case of step, drum Accu
Due to the action of the murator, it is pressed against the solidified shell with excellent followability, and even when the thickness of the slab suddenly decreases after the nodule,
It follows forcefully and quickly to apply a rolling force stronger than in the first step, so that even if shell washing occurs in a part of the slab, cooling of the slab is delayed in that part. Since no slab has a weak point of poor cooling, there is no danger that the slab will be broken by tension during the guiding of the slab to cause trouble. When the rotation speed of the drum increases, shell washing hardly occurs.

When the shell washing no longer occurs, the second hydraulic supply system communicating with the accumulator is shut off,
The hydraulic pump and the hydraulic cylinder are connected by the first hydraulic supply system, and a state of continuous casting is achieved. In this state, pressure oil whose pressure has been adjusted is supplied to the pair of hydraulic cylinders, and pressure reduction control is performed so that one drum is parallel to the other drum. At this time, since the rotation speed of the drum is sufficiently high, shell washing hardly occurs. Therefore, an excellent cast piece having a constant thickness can be obtained while suppressing the wedge amount to a low level.

[0010]

FIG. 2 shows an example of a twin-drum type thin plate (steel plate in this example) continuous casting apparatus 1 for practicing the present invention. While being cooled by such a cooling medium, they are rotationally driven in opposite directions (directions of arrows) at the same rotational speed by a drive mechanism (not shown). The twin-drum thin-sheet continuous casting apparatus 1 includes a pair of bearings 6, 6 and 7 that rotatably support both ends of the shafts 4 and 5 of the drums 2 and 3, respectively.
7 (FIG. 1 shows only the bearings 6 and 7 on one end side of the shafts 4 and 5; the same applies hereinafter) and a common frame 8 (the phantom line) supporting those bearings 6, 6 and 7, 7. And hydraulic cylinders 9, 9 respectively provided between the bearings 7, 7 and the frame 8 to define the positions of the bearings 7, 7 of the drum 3 with respect to the bearings 4, 4 of the drum 2, respectively. Load detectors (load cells) 10 and 10 are provided between the bearings 6 and 6 to detect a load (reaction force) acting on the bearings 6 and 6.

The distance between the drums 2 and 3 is determined by the hydraulic cylinder 9,
The distance between the bearings 7 is determined by the position of the bearings 7 determined by 9, and the interval thereof is a main factor that determines the thickness of the continuously cast slab. Above the gap between the drums 2 and 3, a pool 1 whose side is partitioned by a side weir (not shown)
1 is formed, and a nozzle of the tundish (not shown) extends into the pool 11, and the nozzle supplies molten steel (in general, molten metal) into the pool 11. The molten steel supplied into the pool 11 is cooled where it contacts the surfaces of the drums 2 and 3, solidifies to form a shell 12, and the drums 2 and 3 are driven to rotate in the directions of the arrows. It passes through the narrowest gap between the drums 2 and 3 and receives a rolling force to form a strip-shaped slab 13 which is continuously fed downward. The fed slab 13 is further cooled while being guided by a pinch roller or the like (not shown), and is finally wound up by a coiler. When continuous casting is performed, the drum 3 is pressed and supported toward the drum 2 by the hydraulic cylinders 9, 9, whereby the slab 13 (shell 12) sandwiched between the drums 2, 3 exerts a rolling reduction force. Acts, and a corresponding reaction force is detected in the load detectors 10, 10.

The main part of the twin-drum continuous sheet casting apparatus 1 shown in FIG. 2 is simplified and shown in FIG. At the bottom of the pool 11, the molten steel solidifies to form the shell 12, so that the rotating speed of the drums 2 and 3 is 0 at the start-up (start-up) of the twin-drum thin-sheet continuous casting apparatus 1.
In the process of gradually increasing from the tip 1 of the slab 13 which is fed out while the rotational speed immediately after the start is still low.
4, the time for cooling the unit volume of molten steel becomes relatively long, so that the thickness of the shell 12 temporarily increases, and the vicinity of the tip (bottommost portion) 14 of the slab 13
A bump 15 as shown in FIG. Therefore, immediately after starting, the drums 2 and 3 must push the knob 15 out of the narrow gap formed between them. If the knob 15 is too large, the conventional twin-drum continuous thin-plate continuous casting apparatus 1 cannot pass through the knob 15 because the drum support mechanism has no elasticity and cannot be started.

FIG. 5 shows a continuous casting by a twin-drum type thin plate continuous casting apparatus 1 having a drum diameter of 1200 mm.
The frequency of the position where the peak of the bump 15 appears is actually measured and plotted on the vertical axis, and the position is not directly represented by the length on the slab 13 (cast length), but the drum 2 corresponding to the cast length. Alternatively, the value converted into the angle (arc angle) θ of the circular arc of 3 is shown on the horizontal axis. As can be seen from FIG. 5, the bump 15 appears when the arc angle θ is in the range of 5 degrees to 10 degrees, and shows the maximum value of the frequency at an intermediate position.

As another factor for changing the thickness of the bottom portion of the slab 13 formed at the start-up of the twin-drum continuous sheet casting apparatus 1, the shell once formed at the bottom of the pool 11 as described above is used. Even if “shell washing” occurs in the width direction or vertical stripes on the slab 13 due to the partial re-melting of the subsequent molten steel by the subsequent molten steel, other parts of the shell washing part As a result of the delayed cooling by the drums 2 and 3 compared to the part, the thickness of the part is reduced. Shell washing occurs when a part of the shell 12 once formed receives the heat of the subsequent molten steel and re-melts. Therefore, when the rotation speed of the drums 2 and 3 is low, that is, the surfaces of the drums 2 and 3 are hot water. This is more likely to occur when the pool portion 11 is in contact with molten steel for a long time.

Thus, the time from when any point on the surface of the drum 2 or 3 enters the surface of the pool 11 to when it exits, that is, the time required for passing through the angle (arc angle) α shown in FIG. Is the contact time of molten steel (generally speaking, contact time of molten metal)
FIG. 6 shows the frequency of occurrence of shell washing with respect to the molten steel contact time, and shows the molten steel contact time on the horizontal axis and the frequency of shell washing on the vertical axis. The occurrence of shell washing was determined by the change in the thickness of dendrite in the cross section of the slab. From FIG. 6, it can be seen that shell washing starts to occur when the molten steel contact time is 0.8 seconds or longer, and the frequency of shell washing increases as the molten steel contact time increases. However, according to the continuous casting speed in the steady state, the molten steel contact time is 0.8
If the rotation speed of the drums 2 and 3 is increased to a steady state as soon as possible at the start-up, no shell washing will occur thereafter, and the weakness of the slab 13 due to the shell washing will occur. There is no danger of the slab breaking.

As described above, at the time of startup, the slab 13
If the problem of the nodule 15 and the shell washing, which are factors of the thickness variation appearing at the bottom portion near the tip of the shell, can be solved,
The twin-drum continuous casting machine 1 can be smoothly shifted to a continuous casting state without any difficulty in starting or breaking the slab.

Therefore, according to the present invention, a hydraulic system as illustrated in FIG. 1 is used to start the engine from the third step as in the prior art. , The twin-drum thin sheet continuous casting apparatus 1 can be started smoothly, and the above problem can be solved.

The hydraulic system illustrated in FIG. 1 determines the position of the drum 3 and applies a pressure to the hydraulic cylinders 9, 9 attached to the bearings 7, 7 in order to apply a necessary rolling force to the slab 13. It consists of a hydraulic circuit that supplies oil.
The hydraulic cylinder 9 is of a double-acting type, and a first chamber 20 and a second chamber 21 before and after the piston are connected to a hydraulic pump 25 via a servo valve 22 and an electromagnetic switching valve 24. When the valve 24 is opened, the supply of pressure oil whose pressure is finely adjusted by the servo valve 22 is received. The first chamber 20 and the second chamber 21 of the hydraulic cylinder 9 are communicated when the electromagnetic switching valve 26 is opened. The second chamber 21 has an electromagnetic switching valve 27 and a relief valve 28.
The pressure oil can be discharged to the reserve tank 29 via the second valve 21 so that the second chamber 21 can be maintained at the set hydraulic pressure. The servo valve 22 and the electromagnetic switching valves 24, 26, and 27 are all controlled to open and close by a control device (not shown). As the servo valve 22, a highly responsive electromagnetic valve capable of controlling the duty ratio or an equivalent one is used.

According to the present invention, a second hydraulic supply system including an accumulator 31 in parallel with the system 30 is provided separately from the first hydraulic supply system 30 that supplies pressure oil via the electromagnetic switching valve 24 and the servo valve 22. 32 are provided. The second hydraulic supply system 32 connects the hydraulic pump 25 and the first chamber 20 of the hydraulic cylinder 9 by connecting an electromagnetic switching valve 33 and an electromagnetic switching valve 34 in series, and connects the electromagnetic switching valves 33 and 34 to each other. An accumulator 31 is connected therebetween. The accumulator itself is also called a shock absorber, and is known to be used for a fluid circuit such as a hydraulic circuit. The accumulator compresses an air chamber or an elastic body formed therein to form a second hydraulic supply system 3.
By temporarily accumulating the hydraulic pressure acting on 2,
It has a cushioning function to mitigate a sudden rise in hydraulic pressure. The electromagnetic switching valves 33 and 34 are also opened and closed by a control device (not shown). The hydraulic cylinder 9 is provided on each of the two bearings 7 of the drum 3, and the hydraulic circuit for driving it is also provided on each of the two hydraulic cylinders 9. It can also be shared between.

In accordance with the features of the present invention, in the embodiment shown in FIG. 1, the electromagnetic switching valves 24, 26, and 2 are controlled by a controller (not shown) at the timings shown in the table of FIG.
By controlling the opening and closing of each of 7, 33 and 34 respectively, after the first step and the second step at the start-up of the twin drum type continuous continuous casting apparatus 1, the state is shifted to the steady continuous casting state of the third step. Can be.

The first step is to start the rotation of the drums 2 and 3 from a stationary state until the peak of the bump 15 of the slab 13 shown in FIG. 4 passes through the narrowest gap between the drums 2 and 3. This time corresponds to the length x from the tip (bottommost portion) 14 of the slab 13. During this time, if the bump 15 of the slab 13 can pass through the gap between the drums 2 and 3 with relatively little resistance, the start of the twin-drum continuous sheet casting apparatus 1 will not be disabled. The arc angle θ at which the bump 15 appears varies depending on the cooling capacity of the drum and the type of metal to be cast. Therefore, in the first step, the relationship shown in FIG. 5 is obtained in advance, and the first step can be determined from the time corresponding to the arc angle θ.

In the first step shown in the table of FIG. 1, the electromagnetic switching valve 24 and the electromagnetic switching valve 27 are closed (OFF), and the relief circuit by the first hydraulic pressure supply system 30 and the relief valve 28 is formed. blocked Rutotomoni, electromagnetic switching valve 33 and 34 is opened (ON), the second hydraulic supply line 32
The pressure oil of the hydraulic pump 25 is supplied to the first chamber 20 of the hydraulic cylinder 9 via the hydraulic pump 9. At this time, since the electromagnetic switching valve 26 is also opened, the first chamber 20 and the second chamber 21 communicate with each other, and the pressure oil is supplied to the second chamber 21 at the same time .
The differential pressure between the two chambers 21, that is, the effective pressure acting on the hydraulic cylinder 9
Although the effective hydraulic pressure becomes substantially zero, the effective area on the front and back of the piston 35 of the hydraulic cylinder 9 is larger by the cross-sectional area of the piston rod 36 on the first chamber 20 side than on the second chamber 21 side. The bearing 7 and the shaft 5 are pressed to the left in FIG. 1 by a relatively small force generated by the hydraulic pressure of the first chamber 20 acting on the difference between the two. In this case, the bump 15 of the slab 13
Is strong and shell washing is not a problem, so the rolling force should be about 1 kg per 1 mm of length in the drum axis direction (800 kg for a drum having a diameter of 1200 mm and a width of 800 mm) or more. Is
Any rolling force that does not hinder the activation of the drum may be used, and is determined by the size of the drum and the power of the drive motor.

In the first step, the bump 15 located near the tip 14 of the slab 13 as shown in FIG.
And 3, the reaction force acting on each bearing due to the passage of the peak of the bump 15 and the corresponding second force
The hydraulic pressure of the hydraulic supply system 32 also tends to increase rapidly, but the force for pressing the drum 3 toward the drum 2 is not only relatively small as described above, but also the second hydraulic supply system 32 has an accumulator. Since 31 is provided,
The sudden increase in hydraulic pressure that occurs when the knob 15 passes through the narrow portion of the gap between the drums 2 and 3 is absorbed by the accumulator 31, and the gap between the drums 2 and 3 opens without great resistance, and The knob 15 of the piece 13 is easily passed. Therefore, there is no danger that the knuckle 15 formed on the slab 13 during startup of the twin-drum continuous thin-plate continuous casting apparatus 1 prevents the apparatus from starting or damages the drums 2 and 3 and the drive mechanism.

When the knob 15 of the slab 13 passes through the narrowest gap between the drums 2 and 3, a control device (not shown) terminates the first step and performs the control of the second step. The second step is a period from the end of the first step until the rotation speed of the drum is increased and shell washing does not occur. The time when shell washing does not occur depends on the shape of the nozzle and the flow rate of the molten metal. to change or the like. Therefore, the second step is part of the slab 13 in advance keep asking the relationship of FIG. 6 or determined from the molten steel contact time, or online
The temperature deviation can be determined from the time until the temperature deviation suddenly decreases . In the second step
A second hydraulic supply system is used. Therefore, the solenoid-operated switching valve 24 is kept closed, and the solenoid-operated switching valves 33 and 34 are kept open, but different from the first step.
Is in the second step is an electromagnetic switching valve 26 is closed by Rutotomoni, electromagnetic switching valve 27 is opened. As a result, the hydraulic pressure in the second chamber 21 of the hydraulic cylinder 9 is reduced by the relief valve 2
8 and the first chamber 20 has the first pressure.
Since the hydraulic pressure from the second hydraulic pressure supply system 32 acts in the same manner as in the step, a larger difference occurs between the hydraulic pressures on both sides of the piston 35 in the hydraulic cylinder 9 than in the first step , and this differential pressure is effective. Acts on hydraulic cylinder 9 as perfect hydraulic pressure
Therefore, the force for pressing the drum 3 to the left via the bearing 7, that is, the rolling force acting on the slab 13 is reduced in the first step.
It increases more than the case .

Even when the second step is entered, the drum 2
And 3 are not yet sufficiently increased, and the thickness of the slab 13 fluctuates greatly due to the occurrence of shell washing, so that the shell is reduced by the increased rolling force as compared with the case of the first step. At the same time, similarly to the first step, the increased oil pressure of the second oil pressure supply system 32 is elastically maintained by the accumulator 31 so that even if there is a change in the thickness of the slab 13, the change in the oil pressure is relatively small. To keep. A
The provision of the accumulator 31 allows the drum 3 to move and follow the variation in the thickness of the slab 13 well.
The distance between the drum 2 and the drum 2 is increased and decreased more quickly than when the control is performed , and the drum 3 is inclined, so that the pressure bonding between the drums 2 and 3 and the shell 12 is performed sufficiently, and the entire surface of the solidified shell 12 is sufficiently formed. Therefore, even if the thickness of the slab 13 fluctuates, there is no portion with low strength that breaks in the middle. In this case, the rolling force in the second step is about 5 to 25 kg / mm per unit length (width) in the drum axis direction, but there is an optimum level depending on the type of steel (generally, the type of metal). The first step and a part of the slab corresponding to the second step, Kunar although such fear of breaking by the practice of the present invention, not suitable for the product if there is deviation in the thickness , Cut in the last step.

In the second step, when the rotational speed of the drums 2 and 3 increases and the molten steel contact time during which shell washing does not occur is reached, the control device ends the second step and switches to the control of the third step. Thereby the usual first
The pressure oil passing through the hydraulic supply system 30 is supplied to the hydraulic cylinder 9.
To press the drum 3. This is because, as described above, when the rotation speeds of the drums 2 and 3 are sufficiently high, the occurrence of shell washing is extremely reduced and the deviation of the shell thickness is reduced. Similarly, steady continuous casting is performed by the drums 2 and 3 rotating at high speed. In the third step, a pair of hydraulic cylinders 9 that support both ends of the shaft 5 of the drum 3 via the bearings 7 move together to keep the drums 2 and 3 parallel in order to keep the amount of the wedge low. By keeping this, the rolling force is controlled so that the thickness of the slab 13 becomes the same value in the width direction.

The control in the third step is substantially the same as that of the prior art. However, as shown in the table of FIG. 1, the control device opens the electromagnetic switching valve 24 while simultaneously opening the electromagnetic switching valve. The valves 27, 33, and 34 are closed to cut off the communication with the accumulator 31 in the second hydraulic supply system 32 and to make the first hydraulic supply system 30 conductive. In this state, the control device finely controls the servo valve 22 to finely adjust the hydraulic pressure of the first chamber 20 and the second chamber 21 of the hydraulic cylinder 9,
The position of the drum 3 is finely moved back and forth through the bearing 7 while maintaining the
Adjust the thickness of the.

In the following Table 1, as an embodiment (case A) of the present invention, in the first step, the accumulator 31 is operated with a hydraulic pressure of 1 ton, and in the second step, the accumulator 31 is operated with a hydraulic pressure of 5 tons. For comparison, four comparative examples in which the accumulator 31 is used or not used for the first step or the second step, or the operating pressure is changed to be large or small even when used, Regarding (cases B to E), the situation of the cast piece 13 confirmed by performing continuous casting experimentally is shown. The common experimental conditions were as follows: drums 2 and 3 had a drum diameter of 1200 mm, a drum width of 800 mm,
Casting speed 80m / min, thickness of slab 13 2.5m
m. From this experimental result, the first step and the second step use the accumulator 31, and the first step
According to the embodiment of the present invention in which the operating pressure in the second step is increased with respect to the step, the start-up is smoother than in the other comparative examples, there is no trouble due to breakage of the slab 13 and the slab having excellent properties It was confirmed that 13 was obtained.

[0029]

[Table 1]

[0030]

According to the present invention, at the start-up of a twin-drum continuous casting apparatus for thin sheets, a notch having a very large thickness formed on a slab can be easily passed therethrough. There is no danger that the drum or the drive mechanism will not be damaged. In addition, even if the thickness of the slab changes due to shell washing before the rotation speed of the drum becomes sufficiently high, the cooling of the slab is achieved by the drum moving closely following the slab. Since it is performed sufficiently, there is no danger that the strip-shaped slab breaks at the shell washing portion due to tension while being guided to the coiler and causes trouble. After the rotation speed of the drums becomes sufficiently high, the pair of drums is kept parallel to perform the rolling reduction, so that an excellent cast piece having a small wedge amount and a constant thickness can be obtained.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing an embodiment of a hydraulic system used in a twin-drum thin sheet continuous casting apparatus of the present invention.

FIG. 2 is a front view showing a main part of a twin-drum thin sheet continuous casting apparatus.

FIG. 3 is a front view conceptually showing a main part of a twin-drum thin sheet continuous casting apparatus.

FIG. 4 is a sectional view showing a slab at the time of starting.

FIG. 5 is a graph showing the frequency of appearance of a bump on a slab.

FIG. 6 is a graph showing the frequency of occurrence of shell washing on a slab.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Twin drum type continuous thin-plate casting apparatus 2, 3 ... Drum 4, 5 ... Shaft 6, 7 ... Bearing 8 ... Frame 9 ... Hydraulic cylinder 10 ... Load detector 11 ... Hot-water pool part 12 ... Shell 13 ... Cast piece 14 ... Tip of cast slab (bottom bottom part) 15 ... knob 20 ... first chamber 21 ... second chamber 22 ... servo valve 24, 26, 27, 33, 34 ... electromagnetic switching valve 25 ... hydraulic pump 28 ... relief valve 29 ... Reserve tank 30 First hydraulic supply system 31 Accumulator 32 Second hydraulic supply system 35 Piston 36 Piston rod

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yasuhiro Yamagami 20-1 Shintomi, Futtsu-shi, Chiba Nippon Steel Corporation Technology Development Division (72) Inventor Hideki Oka 3434 Shimada, Oji, Hikari-shi, Yamaguchi Shin-Nippon (72) Inventor Yoichi Wakiyama 4-2-2 Kannon Shinmachi, Nishi-ku, Hiroshima, Hiroshima Prefecture Mitsubishi Heavy Industries, Ltd. No. 6-22, Mitsubishi Heavy Industries, Ltd. Hiroshima Works (56) References JP-A-2-80160 (JP, A) JP-A-59-193740 (JP, A) Jpn. Hirakai 3-119024 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) B22D 11/06 B22D 11/16

Claims (3)

(57) [Claims] A basin that is cooled by a cooling medium such as water circulating in the inside thereof, is driven to rotate in opposite directions at the same rotation speed, and is supplied with a molten metal above the gap therebetween. A pair of drums to be formed, a bearing that rotatably supports both ends of shafts of the pair of drums, a common frame that supports the bearings, and a shaft that supports both ends of the shaft of one of the drums, respectively. A first hydraulic pressure that is provided between a bearing and the frame and that couples a pair of hydraulic cylinders that determine the position of the one drum with respect to the other drum, and a hydraulic pump that supplies hydraulic oil thereto; A supply system, and a second hydraulic supply system having an accumulator in a parallel relationship with the first hydraulic supply system and switchable therewith. Twin-drum continuous casting machine. 2. The method according to claim 1, wherein in the first step from the time of activation to the time when the slabs of the slab pass through the narrowest gap between the pair of drums, using the twin-drum continuous sheet casting apparatus of claim 1. the pressure oil under the accumulator intervention by two hydraulic supply system is supplied to the hydraulic cylinder, resiliently give pressure under force to the drum of the one, after the first step is completed, the drum In the second step until the rotation speed increases and the shell washing does not occur, the second hydraulic supply system supplies the hydraulic oil having a higher pressure than that in the first step under the intervention of the accumulator. A third step, which is a state of continuous continuous casting after the completion of the second step, is supplied to the cylinder to elastically apply a greater rolling force to the one drum than in the first step. In the pump, the second hydraulic supply system is switched to the first hydraulic supply system, the accumulator is shut off, pressure-adjusted pressure oil is supplied to the pair of hydraulic cylinders, and the one A twin-drum thin plate continuous casting method, comprising: performing a rolling reduction control so that a drum is parallel to the other drum. 3. A puddle part cooled by a cooling medium such as water circulating in the inside, driven to rotate in opposite directions at the same rotation speed, and supplied with a molten metal above the gap therebetween. A pair of drums to be formed, a bearing that rotatably supports both ends of shafts of the pair of drums, a common frame that supports the bearings, and a shaft that supports both ends of the shaft of one of the drums, respectively. A pair of hydraulic cylinders provided between the bearing and the frame to determine the position of the one drum, and a first hydraulic supply system connecting the hydraulic cylinder and a hydraulic pump that supplies hydraulic oil thereto. In the twin-drum type continuous sheet casting apparatus, in a parallel relationship with the first hydraulic supply system,
A second hydraulic pressure supply system including an accumulator is provided so as to be switchable therewith, and in the first step from the time of activation to the point where the cast stub passes through the narrowest gap between the pair of drums, the pressure oil under the accumulator intervention by two hydraulic supply system is supplied to the hydraulic cylinder, resiliently give pressure under force to the drum of the one, after the first step is completed, the drum In the second step until the rotation speed increases and the shell washing does not occur, the second hydraulic supply system performs the first step under the intervention of the accumulator .
Supplying a higher pressure oil than the case to the hydraulic cylinder,
Elastically to the one drum as in the first step.
In the third step, which is a state of steady continuous casting after the completion of the second step, the second hydraulic supply system is switched to the first hydraulic supply system. Shutting off the accumulator, supplying pressure-adjusted pressure oil to the pair of hydraulic cylinders, and performing pressure reduction control such that the one drum is parallel to the other drum. Twin-drum sheet continuous casting method.