JP2000190053A - Method and apparatus for controlling side weir pressing in twin roll continuous casting - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a side dam pressing control method and apparatus for stably sealing molten steel against disturbance generated during casting in twin-roll continuous casting for producing a thin plate slab. . SOLUTION: An increase in a reaction force measured by a load cell attached to a drum 1 or a load cell 4 attached to a reduction cylinder 3 of a side dam 2 is detected, and the side dam 2 and the drum 1 are instantaneously adjusted to the size. After calculating the pushing amount of the side weir by the arithmetic unit 5 so that no gap is opened between them, the pushing-down cylinder 9 of the side weir is driven by the pushing control unit 6 of the side weir in real time based on the calculation result to determine the pushing amount. A method and an apparatus for controlling a side weir pressing in a twin-roll continuous casting characterized by controlling.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling side dam pressing for stably sealing molten steel against disturbance generated during casting in twin-roll continuous casting for producing thin slabs. .

[0002]

2. Description of the Related Art A method of producing a thin sheet slab by continuous casting using a twin-roll continuous casting machine is to introduce molten metal between a pair of cooled horizontal casting drums rotating in opposite directions, and apply the molten metal onto a rotating roll surface. To solidify the metal shells in the gap between the drums, and combine the metal shells in the gap between the drums, and feed the solidified thin plate slab downward from the gap between the drums. The end of the drum is sealed with a side dam to cast thin slabs,
When the molten metal in contact with the side weir adheres and accumulates on the side weir surface moves downward along the side weir surface and bites into the minimum gap position between the drums, the thickness of the ingot becomes smaller than that of the aforementioned drum. If it is larger than the minimum gap between them, the metal will be rolled by the rotating drum. In this case, the intrusion of the metal appears in the reaction force of the drum, and it has been found from operational experience that 10 to 20% of the increase in the reaction force of the drum is the increase in the reaction force of the side dam. This means that the metal is extended not only in the casting direction but also on the side weir side by rolling, causing a widening phenomenon. You will receive power instantly. Normally, such a force lasts for several hundred milliseconds (msec), and the force generated during this time pushes the side weir installed on the support device of the elastic structure, and retreats, thereby bringing close contact between the drum and the side weir. There is a gap in Once such a gap is formed, molten steel is inserted into the gap and the solidified slab rotates with the drum, damaging the surface of the side weir that comes into contact with the drum. There is a problem that a slab end defect frequently occurs due to a slab break due to a band or an ingot sticking to a side weir.

[0003] Particularly, in the production of sheet slabs in twin-roll continuous casting, this hot band tends to occur frequently. In the hot band, foreign matters such as ingots and refractory fragments are caught in the solidified shell during casting, and the thickness of the cast piece temporarily increases at that portion. When the slab portion that has caught the foreign matter passes through the gap between the pair of drums, the gap between the pair of drums instantaneously increases due to slight elastic deformation of the drum and the portion supporting the drum. At the same time, the reaction force at the support portion of the drum also increases, and the rolling force of the drum at that time acts intensively on the foreign matter biting portion,
Since the slab does not act on the entire area of the slab in the width direction, heat removal of the slab in that part, that is, cooling is deteriorated, the temperature becomes high, and a hot band is formed. When this hot band occurs, the slab breaks or breaks out, and the casting becomes impossible.

[0004] Various improvements have been proposed to solve this problem. One example is disclosed in
Japanese Patent Application Laid-Open No. 215254 proposes a method of detecting the opening amount of the side weir with respect to the drum end surface, and increasing the drum rotation speed to return to a predetermined value when the opening amount exceeds a predetermined value. JP-A-59-215255 proposes a method of raising and lowering a side weir according to the amount of opening of the side weir with respect to the drum side surface. Further, Japanese Unexamined Patent Publication No.
In JP-A-3-36954, the amount of change in the gap between the side weir and the drum end surface during casting is detected (or calculated) in consideration of the axial thermal expansion allowance of the drum, and when the actual gap changes with respect to the predetermined gap, A method has been proposed in which the pressing force of the side weir is increased / decreased and returned to a predetermined gap so as to control the gap and the pressing force so that unnecessary pressing force does not occur.
Further, Japanese Patent Laid-Open No. 4-22849 proposes a method of controlling the timing of pressing the upper and lower sides of the side weir when the side weir is pressed against the drum end surface.
Japanese Patent Application Laid-Open No. Hei 5-269553 discloses a method of controlling the pressing of a side weir by using a plurality of position control cylinders and a reaction force detecting device attached thereto to prevent the side weir from being inclined. When the sum of the reaction forces of each of the members falls below a predetermined value for each elapsed time from the start of casting, the position control cylinders of the side dams are simultaneously actuated to perform the pressing control of the side dams. A method has been proposed.

[0005]

However, in spite of these proposals, the molten steel seal is still unstable due to disturbance during casting, and a gap is formed between the drum and the side weir. While the molten metal is inserted and solidified, the metal contacts the drum of the side weir while rotating together with the drum, and damages the surface of the side weir, which deteriorates the sealing properties of the molten steel at an accelerated rate. The problem of frequent occurrence of slab edge defects due to gold adhesion has not yet been solved.

That is, the opening amount of the side weir proposed in JP-A-59-215254 and JP-A-59-215255 is detected, and when the opening amount exceeds a predetermined value, the drum speed is reduced. It has been found that the method of increasing the speed or raising and lowering the side weir to return the opening amount to a predetermined amount is not effective from the viewpoint of responsiveness to the phenomena targeted by these methods. Also, in order to change the pressing force when a predetermined value is exceeded while monitoring the gap between the side weir and the drum end surface proposed in JP-A-63-36954, a steady casting state in which the state changes relatively slowly. Although this is an effective means, it has a problem that it cannot catch up with an unsteady phenomenon that occurs instantaneously due to the bite of metal. On the other hand, it can be said that the means relating to the control timing proposed in Japanese Patent Application Laid-Open No. 4-32849 is not an effective means for preventing the seal failure due to the bite of the metal. In addition, the method proposed in Japanese Patent Application Laid-Open No. 5-269553 is a method of simultaneously issuing an operation instruction to the position control cylinder of the side weir when the reaction force of the side weir falls below a predetermined value. However, this is also not an effective means for preventing a sealing failure caused by an instantaneous increase in the reaction force caused by the bitten metal.

[0007]

SUMMARY OF THE INVENTION The present invention is directed to a twin-roll continuous casting for producing a thin sheet slab, in which the deposited metal adheres and accumulates on the side weir surface and moves downward along the side weir surface. The present invention proposes an effective means against a phenomenon that causes an unsteady sealing failure that occurs instantaneously when the drum is caught in the minimum gap position between the drums. When performing sealing by side dams from operational knowledge, in a steady casting state, a high-precision position control function having a resolution of 0.5 μm or less in accordance with the wear rate of refractory caused by contact with the end of the drum, On the other hand, 10m when hot band occurs
Responsiveness that moves at a high speed of m / sec or more is required. It is essential to have both functions during the casting operation. Therefore, in order to provide a function for operating the side weirs with high accuracy and high speed in response to such a need, a high-precision positioning device and a high-speed moving device constitute an operating function, and hot band generation and The aim is to optimize the movement of the side weir in response to the disturbance during casting. That is, the present invention is a twin-roll continuous casting in which molten steel is poured into a portion surrounded by the pair of rotating drums and the side weir, both ends of which are sealed by a pair of drums opposed in parallel with side dams. In particular, the present invention relates to a method for controlling a side weir pressing in twin roll continuous casting, which is characterized by securing a stable molten steel seal against disturbance generated during casting. The gist of the method is as follows.

(1) An increase in the reaction force measured by a load cell attached to the bearing box of the drum or a load cell attached to the pressure reduction cylinder of the side weir is detected, and the distance between the side weir and the drum is instantaneously adjusted to the size. After calculating the amount of pushing of the side weir by the arithmetic unit so that no gap is opened, control the pushing amount by driving the high-speed reduction cylinder of the side weir by the side weir pressing controller in real time based on the calculation result. A method for controlling a side weir pressing in twin roll continuous casting.

(2) A load cell attached to the bearing box of the drum to detect the reaction force of the drum, a load cell attached to the pressure reduction cylinder of the side dam to detect the reaction force of the side dam, and detection by one or both of these load cells. A twin roll comprising: a calculating device for calculating a pushing amount of the side weir based on the increased reaction force, and a pushing amount control device for transmitting the pushing amount to the high-speed reduction cylinder of the side weir based on the calculation result. Side weir pressing control device in continuous casting.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS According to the present invention, it is possible to detect the above-mentioned phenomenon of intrusion of metal, which causes a defective seal, by detecting an increase in the reaction force of the drum or an increase in the reaction force of the side dam. Paying attention, the fluctuation of the drum reaction force is detected by the load cell attached to the bearing box of the drum, or the increase in the reaction force of the side dam is directly detected by the load cell attached to the reduction cylinder of the side weir, and the pressing force of the side weir is detected. By changing it, it is intended to prevent deterioration of the sealing performance. The metal entrapment phenomenon is detected by the increase in the reaction force measured by the load cell attached to the drum's bearing box or the load cell attached to the side weir pressing cylinder, and the side weir and the drum are instantly adjusted to their size. After calculating the amount of pushing of the side weir with an arithmetic unit so that no gap is opened between them, the pushing amount of the side weir is increased by driving the high-speed reduction cylinder of the side weir by real-time pressing control of the side weir based on this calculation result, It is possible to prevent poor sealing due to the bite of the metal. The high-speed rolling cylinder has a response with a rolling speed of 10 mm / sec or more.

The phenomenon associated with the ingot of metal occurs instantaneously, and the force acting on the side weir side increases, so that an immediate response is required. However, the side dam pressing control method according to the present invention can sufficiently cope with this. And it is possible to prevent the seal failure due to the fall of the bullion. By the way, since the side weir is normally pressed against the drum end face with a constant pressing force to seal the molten steel, it will not appear as a displacement unless the force on the side weir side accompanying the metal ingot becomes more than this pressing force . Accordingly, if the pressing force is controlled while detecting the displacement of the side weir, the problem cannot be solved in a timely manner from the viewpoint of preventing a gap.

The present invention will be described in detail with reference to FIGS. FIGS. 1 and 2 are schematic diagrams showing a specific control method of the side dam pressing control method according to the present invention.
In each figure, a side weir 2 for sealing molten steel is provided at an end of a drum 1, and a load cell 7 for detecting a drum reaction force is provided between a bearing box 10 of the drum 1 and a frame 11 supporting the same. Fluctuations in the drum reaction force during operation are constantly detected. The press-down cylinder 3 for positioning the side weir 2 against the drum 1 for high-precision positioning is electrically driven,
Any type of hydraulic system may be used, generally 0.5 μm
This cylinder has a fine resolution and excellent position control characteristics. Then, the pressing cylinder 3 and the drum 1
A load cell 4 for constantly measuring a side dam reaction force or an increase in the side dam reaction force is provided between the carriage 8 and the side wall of the carriage 8 which can move in a direction parallel to the axis. On the other hand, the carriage judge 8 is provided with a high-speed hydraulic cylinder 9 as a side weir pressing device, and is configured to be able to operate instantaneously in response to a change (fluctuation) of the carriage judge 8. That is, the increase in the reaction force of the side weir 2 is directly detected by the roll cell 4, and the pressing force of the side weir 2 is changed to prevent the deterioration of the sealing performance. Further, as a specific method of controlling the pressing of the side weirs, when a metal squeezing phenomenon occurs, the reaction force of the drum increases, and the increased margin is applied to the load cell 1 attached to the bearing box 10 of the drum.
2 or the reaction force of the side weir 2 is also increased. Therefore, this increase is measured by a load cell 4 attached to a reduction cylinder 3 connected and connected to the side weir, and the detected values are calculated. The calculation unit 5 calculates an appropriate pushing amount of the side weir according to the size of the increase in the arithmetic unit 5. For example, in the arithmetic unit 5, the change gradient of the reaction force is calculated, and at the moment when this value exceeds a certain "threshold value", the result is transmitted to the pushing amount control device 6 in real time, and the high speed of the side weir is controlled. By driving the pressing cylinder 9 to increase the amount of pushing in the side weir, and apparently changing the rigidity of the side weir 2, control is performed so that no gap is opened between the side weir 2 and the drum 1.

[0013]

As described above, according to the present invention, the method for controlling the pressing of the side weir in the twin roll type continuous casting for producing a thin plate slab is not limited to the clearance between the side weir and the drum against the disturbance generated during the casting. Continuous casting that can stably seal the molten steel so as not to open.

[Brief description of the drawings]

FIG. 1 is a schematic plan view showing the configuration of a side dam pressing control device according to the present invention.

FIG. 2 is a schematic side view showing the configuration of a side dam pressing control device according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Drum 2 ... Side weir 3 ... High-precision positioning press-down cylinder 4 ... Load cell 5 ... Computing device 6 ... Pushing amount control device 7 ... Load cell 8 ... Carriage 9 ... High-speed hydraulic cylinder 10 ... Drum bearing box 11 ... Frame 12 ... Hot water sliding part 13: cast slab

Claims (2)

[Claims] 1. An increase in reaction force measured by a load cell attached to a bearing box of a drum or a load cell attached to a reduction cylinder of a side weir is detected, and instantaneously adjusted between the side weir and the drum in accordance with the size. After calculating the pushing amount of the side weir with the arithmetic unit so that the gap is not opened, based on the calculation result, drive the high-speed pressing cylinder of the side weir by the side weir pressing control device and control the pushing amount in real time. Characteristic control method for side dam pressing in twin roll continuous casting. 2. A load cell attached to a bearing box of the drum to detect the reaction force of the drum, a load cell attached to a pressure reduction cylinder of the side weir to detect the reaction force of the side weir, and a load cell detected by one or both of these load cells. A twin-roll type comprising an arithmetic unit for calculating the amount of push-in of the side weir based on an increase in the reaction force, and a push-in amount control device for transmitting the amount of push-in to the high-speed reduction cylinder of the side weir based on the calculation result. Side weir pressing control device in continuous casting.