JPH02247050A - Continuous casting method and apparatus thereof by twin roll - Google Patents

Abstract

PURPOSE:To prevent the development of molten metal leakage and wear of short side weirs by ascending/descending the short side weir in sliding contact with end faces of mold rolls and adjusting the lower end of the weir so as to correspond to confluent position of solidified shell. CONSTITUTION:A cast slab 22 is continuously drawn from one pair of mold rolls 1, 1 mutually arranged as parallel. In the above continuous casting method by twin rolls, the lower end 5a of the short side weir 5 in sliding contact with the end faces of the mold rolls 1, is made to correspond to the confluent position A of the solidified shell 11 formed on the peripheral surfaces of the mold rolls 1. Further, a movable piece 17 is set in contact with the lower end part of the short side weir 5 and abutted on the end faces of the mold rolls 1, and a dummy bar (not shown in the figure) is inserted and the molten steel is poured to start casting. By this method, leakage of the molten steel is prevented. After that, according to the casting velocity Vc, a motor 15 for driving rolls is controlled, and also by controlling a lifting jack 7 with a control unit 12, the lower end 5a of the short side weir 5 is always made to correspond to the variable confluent position A. By this method, the confluent solidified shell 11 is forced out and cooled, and the wear of the short side weir 5 and molten steel leakage are prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a continuous casting method using twin rolls and an apparatus therefor, in which a slab is continuously drawn from between mold rolls arranged parallel to each other.

2. Description of the Related Art In twin-roll continuous casting equipment in which a slab is continuously drawn from between a pair of mold rolls arranged parallel to each other, the solidified shell formed on the circumferential surface of the mold 1:7 is closest to the mold rolls. The two parts merge near one side to form a slab. If the molten steel weir that supplies molten steel between these mold rolls is configured, for example, by a pair of short side weirs that span the end faces of the mold rolls, the solidified shells are merged and compressed from the merging part of the solidified shells to the closest part of the mold rolls. The shell is extruded from the side end face of the slab, and the stress of the extruded shell creates a gap between the short side weir and the end face of the mold roll, and molten steel sometimes enters this gap, causing trouble.

In addition, the sliding resistance of the extruded shell part increases, and the - part of the solidified shell gets caught on the short side weir, and the width of the slab to be pulled out becomes narrow. Also, if the caught part becomes large to a certain extent, the slab is removed all at once. If they were pulled out together, unevenness would occur on the side edges of yiJ"1, which could cause tearing or breakout of the slab.

Therefore, for example, in JP-A No. 63-622/11 and JP-A-63-62243, an intermediate weir provided between the end weirs or a side end layer divided into two halves is There has been proposed a device that moves downward at a predetermined speed along the drawing direction.

Problems to be Solved by the Invention However, according to the above-mentioned conventional configuration, the intermediate weir or side end layer requires a downwardly long intermediate weir or side end layer of 10 to 60 Ib -1, which is extremely uneconomical. .

The present invention solves the above-mentioned problems and prevents short side weir wear and breakage caused by shells extruded from the solidified shell merging section, and is an economical continuous casting method in twin-roll type continuous casting equipment. and to provide molten steel weirs.

In order to solve the problems described in "Means for Solving the Problems", the continuous casting method of the present invention provides a continuous casting method in which when a slab is continuously pulled out from between a pair of mold rolls arranged parallel to each other, both mold rolls 17 - The lower end of the short side weir that slides into contact with the end surface of the mold roll corresponds to the merging position of the solidified shell formed on the peripheral surface of the mold roll, and the lower end of the short side weir and the position corresponding to the closest part of the mold roll are arranged. A dummy bar is inserted between the mold rolls to supply molten steel, and then the dummy bar is pulled out to start casting, and the movable piece is separated from the mold roll to form a solidified shell. The short side weir is raised and lowered in response to changes in the merging position, so that the lower end of the short side weir corresponds to the solidified shell merging position.

Further, the continuous casting device of the present invention is a twin-roll type continuous casting device that continuously pulls slabs from between a pair of mold rolls arranged parallel to each other, and the lower end is in sliding contact with the end surfaces of both mold rolls. A short side weir located near the upper part of the closest part is provided so as to be able to rise and fall freely, and an elevating device is provided to move the short side weir up and down. A control device is provided to control the elevating device so as to follow the lower end position of i!, and a movable piece extending over a position corresponding to the lower end of the short side weir and the closest part of the mold roll is brought into contact with the end face of the mold roll i! It is something that can be set up for an extended period of time.

Effect With the above configuration, the movable piece closes the gap between the dummy bar and the short side weir at the end of the mold roll at the start of the mold roll to prevent leakage of molten steel, and after the start of casting, the solidified shells join together to close the gap between the dummy bar and the short side weir. The shell that is extruded out is not constrained and cools. Therefore, the short side weir is not pressed by the extruded shell and a gap is not created between the short side weir and the mold roll, and the short side weir is not worn and causes a breakout. In addition, since the short side weir is lowered four times in accordance with the solidified shell confluence position which varies depending on the casting speed, even if the B-forming speed is changed, there will be no occurrence of melt leakage or wear of the short side weir.

Example An embodiment of the present invention will be described below based on the drawings.

As shown in FIG. 2, a molten steel receptacle 3 for receiving molten steel 2 is disposed on a pair of left and right mold rolls 1°1 which are arranged parallel to each other at regular intervals. This molten steel receiver 3
consists of a pair of short side weirs 5, 5 which are in sliding contact between the end faces of the mold rolls 1, 1 and whose lower ends 5a are located above and near the closest portion 4 of the mold rolls 1, 1. This short side weir 5 is formed of refractory material as shown in FIG. (not shown) is pressed against the end surfaces of the mold 1 calls 1, 1 with a predetermined force, and is supported so as to be able to rise and fall freely.

Further, above the short side weirs 5, as shown in FIG. 1, a lifting jack 7 using a worm gear or a screw shaft is provided. Connected to the top. This lifting jack 7 is provided with a position detector 8 that detects the position of the lower end 5a of the short side weir 5, and a lifting motor 7c that drives the lifting jack 7 via a reduction gear 7b has a casting speed. Solidified shell 11 on the circumferential surface of mold roll 1, 1 calculated by vc
A control device 12 is connected to the merging position A of 11 to follow the lower part of the short side weir 5 @5a. Therefore, this control device 1
2, a command signal for the casting speed ■c output from the mold 1 call drive control device 16 is input to the roll drive motor 15 that drives the mold roll 1.1 via the distribution gear 13 and the reducer 14. is configured to be

Below the short side weir 5, a refractory movable shaft extending from the bottom @5a of the short side weir 5 to the closest part 4 to the mold rolls is arranged so as to be able to come into contact with and separate from the end faces of the mold rolls 1, 1. The movable piece 15 has a support member 18 at the bottom of the steel frame 6.
The movable piece 17 is supported by the actuating rod 19a of the cylinder device 19, which is taken through the
As shown in Figure (a), a mold is formed between the short side weir 5 and the dummy bar 20 that is pressed against the end surface of the mold roll 111 by the cylinder device 19 to close the mold roll closest portion 4 at the time of startup. It is configured to close the gap 21 between the end faces of the rollers 1,1. In FIG. 3(b), reference numeral 22 indicates a slab to be drawn, and 22a indicates a shell pushed out from a side end of the slab 22.

Next, the continuous casting method in this example will be explained.

First, lower the short side j[I5.5 @5a, 5a at the casting speed vc
The elevating motor 10.10 of the elevating jack 7.7 is driven to raise and lower the short side weirs 5, 5 so as to correspond to the solidified shell merging position A determined by .

The solidified shell merging position A is determined by the following equation, as shown in FIG.

L is the height from the closest part 4 of the mold roll to the hot water surface 2a, R is the radius of the mold roll 1, and θ is the angle between the closest part A at the roll center 0 and the contact point C of the hot water surface 2a of the mold roll 1. Then, the relationship is θ-5in-1L (2), and if N is the length of the molten steel contact portion on the circumferential surface of the mold roll 1, then θN-πRXηI.

Further, if t is the cooling time, the relationship is as follows: (1) (casting speed VC - circumferential speed of mold roll 1).

If S is the thickness of the solidified shell 11 and K is the solidification coefficient of the molten steel, then the relationship is as follows: 5=KJ (2), and furthermore, D is the thickness of the slab 22, and m is the solidification coefficient of one of the solidified shells. If the compression amount is 11, m and S
N...The relationship is as shown in (3).

Here, if h is the distance from the closest part 4 of the mold roll to the solidified shell joining position A, then h= -R-m
-----------The relationship is as shown in (4), and it becomes.

The above equation (5) is calculated by the control device 12, and the difference between this calculated value and the detected value of the position detector 8 which detects the distance of the lower end 5a of the short side weir 5 from the mold roll closest position 4 is calculated. The elevating motor 7C is driven so that the value becomes 0.

Next, a dummy bar 20 is placed between both molds 17- and 1.1.
At the same time, the cylinder device 19 is extended to press the movable piece 17 against the end surface of the mold roll 1.1, and pouring from the tundish nozzle 23 is started. After a predetermined time has elapsed, the roll drive motor 15 is driven to rotate the mold rolls 1, 1, and the slab 22 is pulled out at a predetermined casting speed Vc. Simultaneously with the start of this casting, the movable roller 17 is separated from the end surfaces of the mold rolls 1, 1 by the cylinder device 19. Note that the movable piece 17 may be separated when a force for pushing out the solidified shell 11 is applied to the movable piece 17.

After the start of casting, when the casting speed ■c is changed, the speed command signal from the mold roll drive control device 16 is transmitted to the control device 1.
2, and the short side weir 5 is moved up and down by the lifting jack 7 in response to fluctuations in the lower end 5a or the solidified shell merging position A.

According to the above embodiment, the lower end 5a of the short side weir 5 is arranged corresponding to the solidified shell confluence position A, and the control device 12
As a result, the solidified shell merging position A, which fluctuates due to changes in the casting speed c, is calculated, and the short side weir 5 is raised and lowered without driving the lifting jack 7, so that the lower end 5a follows the fluctuation of the solidified shell merging position A. , solidified shells 1 that merged at merge position A
1.11 is compressed as the molds 17-rules 1, 1 rotate and are pushed out to the side ends of the slab 22, the short side weir 5
It protrudes downward and is cooled without being constrained. Therefore, as in the conventional case, the extruded shell 22a presses the short side weir 5 and forms a gap between the mold 1' and the I-rule 1, or the short side weir 5 is worn out, causing breakout. It will never be. Note that conventionally, the slab 22 is manufactured by cutting the side edges whose properties are unstable, so there is no need to perform cutting work only for the extruded shell 22a, and the yield of the product does not decrease. do not have.

In addition, in continuous casting, the casting speed is varied between the start-up period when the casting is unstable and the normal operation period when the casting is stable.
Perform at high speed during normal operation. The control device 12 controls the elevating shirt A7 to follow the solidified shell confluence position A that changes due to changes in the casting speed VC, and moves the short side weir 5 up and down to displace the lower end 5a. The shell 22 pushed out presses the short side weir 5, and the molten steel 2 does not leak out due to a gap being created between the lower end of the short side weir 5 and the solidified shell confluence WA.

Furthermore, since the gap 21 between the dummy bar 20 and the short side weir 5 that occurs during startup is closed by the movable piece 17, the supplied molten steel 2 will not leak.

Effects of the Invention As described above, according to the present invention, the gap between the dummy par and the short side weir can be closed by the movable piece at the end of the mold roll at the time of startup, thereby preventing leakage of molten steel. Also,
After the start of casting, the solidified shells merge and are pushed out to the side edges of the slab.The shells are pushed out without being restrained and cooled, so the short side weir is pressed by the pushed out shells, creating a gap between them and the mold rolls. There is no risk of breakouts caused by wear on the short side weirs.

Furthermore, since the short side weir is moved up and down in accordance with the solidified shell confluence position which varies depending on the casting speed, there is no possibility of melt leakage or wear of the short side weir even if the casting speed is changed. Furthermore, since there is no need to move down the weir along the casting direction as in the conventional method, there is no need for weirs that are long in the direction of the upper and lower blades, making it extremely economical.

[Brief explanation of drawings]

The drawings show one embodiment of the present invention, and FIG. 1 is a schematic configuration diagram;
FIG. 2 is an overall perspective view, FIG. 3 (aHb) is a short side @ vertical sectional view for explaining the operation, and FIG. 4 is a schematic explanatory diagram of the calculation formula. DESCRIPTION OF SYMBOLS 1... Mold roll, 2... Molten steel, 3... Molten steel receiver, 4... Mold roll fL approach part, 5... Short side weir, 5a... Lower end, 7... Lifting jack , 11...
- Solidified shell, 12... Control device, 16... Mold roll drive control device, 17... Movable piece, 19... Cylinder device, 20... Dummy par 22... Slab, A
... Solidified shell confluence section, Vc... Casting speed. Agent Yoshihiro Morimoto

Claims (1)

[Claims] 1. When continuously drawing slabs from between a pair of mold rolls arranged parallel to each other, a lower end of a short side weir that comes into sliding contact with the end surfaces of both mold rolls is formed on the peripheral surface of the mold roll. At the same time, a movable piece placed over a position corresponding to the lower end of the short side weir and the closest part of the mold roll is brought into contact with the end surface of the mold roll, and a dummy bar is inserted between the mold rolls. After supplying molten steel, the dummy bar is pulled out to start casting, and the movable piece is separated from the mold roll, and the lower end of the short side weir is moved up and down according to fluctuations in the solidified shell joining position. A continuous casting method using twin rolls, which is characterized by matching the solidified shell merging position. 2. In twin-roll type continuous casting equipment that continuously draws slabs from between a pair of mold rolls arranged parallel to each other, the lower end is located near the upper part of the part closest to the mold rolls, slidingly contacting the end surfaces of both mold rolls. A short side weir is provided so that it can be raised and lowered, and an elevating device is provided to move the short side weir up and down, so that the lower end position of the short side weir follows the confluence position of the solidified shell on the peripheral surface of the mold roll, which is calculated based on the casting speed. A control device for controlling the lifting device is provided, and a movable piece extending over a position corresponding to the lower end of the short side weir and the closest part of the mold roll is provided so as to be able to come into contact with and separate from the end surface of the mold roll. Continuous casting equipment.