JPH04327343A - Method and device for changing mold width in continuous casting impressing static magnetic field - Google Patents

Abstract

PURPOSE:To prevent the development of scratch on surfaces of long side walls in a mold at the time of executing width change in the continuous casting mold during casting by shifting the long side walls along width direction of short side walls in the mold as the releasing holding force of the long side wall in the mold inserting the short side walls in the mold. CONSTITUTION:A holding force releasing mechanism 5 is provided with a holding conversion force converting means for converting suction force in mutual long side walls 1b generated by the impression of static magnetic field into an increase in the holding force, a holding force adding means for adding the preset holding force converted by the converting means and a holding force control means for controlling the holding force based on the value obtd. by the adding means. By the holding force releasing mechanism 5, at least one side of the long side walls 1a, 1b is made to stretch in mutually separating direction so as to eliminate influence of magnetic suction force at the time of changing the width L in the continuous casting mold M. Therefore, in the case of shifting the short side walls 2a, 2b, too, the scratch on the surface of long side walls 1a, 1b is not developed.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] In the field of continuous steel casting, technology has been developed to improve the internal quality of slab strands by controlling the flow of molten steel in a continuous casting mold by applying a static magnetic field. , especially when such technology is applied and the short side wall of the mold is moved in order to change the width of the slab strand without interrupting continuous casting, the long side wall of the mold that holds it in place must be moved. Scratches occurred on the wall of
If casting was continued in this state, there was a risk that this would adversely affect the surface properties of the slab strands. The present invention relates to a mold width changing method and device for continuous casting in which a static magnetic field is applied, and makes effective use of both a technology for improving the internal quality of slab strands and a technology for varying the width of continuous casting molds that is advantageous for improving production efficiency. This is what we are trying to achieve.

0002

2. Description of the Related Art Japanese Patent Laid-Open No. 2-284750 is referred to as a technique for improving the internal quality of continuous casting strands by controlling the flow of molten steel in a continuous casting mold by applying a static magnetic field. According to this technique, it is possible to prevent the molten steel flow from being disturbed and the mold powder to be caught in the mold, and the internal quality of the slab strand can be significantly improved. However, in this method, the long walls of the mold are attracted to each other by the static magnetic field during casting, so the clamping force of the long walls of the mold that pinches the short walls of the mold becomes large. When using this together, scratches are likely to occur on the long side wall of the mold when the short side wall of the mold is moved, and if casting is continued with such scratches, There were disadvantages in that deterioration of the surface properties of the slab strands was unavoidable and, moreover, the life of the mold was extremely short. For this reason, in continuous casting that applies a method of applying a static magnetic field, it is necessary to temporarily interrupt the application of the static magnetic field when changing the width of the mold, but in such a case, the quality of the interrupted area may be affected. Since deterioration is unavoidable, there are many operational problems such as changing the use of only that area or scrapping it in some cases, and there has been a desire to develop a technology that can use both.

0003

[Problems to be Solved by the Invention] An object of the present invention is to enable continuous width variable work during casting to achieve high efficiency production without interrupting the application of a static magnetic field to the mold. The point is to propose possible technologies.

0004

[Means for Solving the Problems] The present invention provides a pair of long side walls of a mold that are provided with magnetic poles for applying a static magnetic field to control the flow of molten steel in the mold, and a pair of long side walls of the mold that are sandwiched between the long side walls of the mold. When performing continuous casting while applying a static magnetic field using a continuous casting mold consisting of a combination of short side walls of the mold, at least one of the long side walls of the mold is pulled in a direction away from each other,
A static magnetic field characterized by relaxing the clamping force of the long walls that sandwich the short walls of the mold, and moving at least one of the short walls of the mold along the width direction of the long walls while maintaining this state. (first invention), and this invention also provides a method for changing the mold width in continuous casting by applying a The mold has a mold formed by combining side walls, and a magnetic pole for applying a static magnetic field for controlling the flow of molten steel in the mold is provided on the back side of the long side wall of the mold, and the short side wall is attached to at least one of the short side walls of the mold. A device for changing the mold width of a continuous casting mold, which is equipped with a moving mechanism that moves the mold along the width direction of the long side wall of the mold, the device having one end connected to the mold frame holding the long side wall of the mold via a pivot pin. A clamping force relief device that connects swingably and connects the other end to a fixed frame of continuous casting equipment to pull at least one of the long walls of the mold away from each other to relieve the clamping force that pinches the short walls of the mold. The clamping force relaxation mechanism includes a clamping force conversion means that converts the attraction force between the long side walls of the mold caused by the application of a static magnetic field into an increase in clamping force, and a clamping force converted by the clamping force conversion unit. A static magnetic field characterized by comprising a clamping force adding means for adding a preset clamping force to the clamping force, and a clamping force control means for controlling the clamping force based on the value obtained by the clamping force adding means. This is a mold width changing device in continuous casting using applied pressure (second invention).

Now, FIGS. 1, 2, and 3 show an example in which a device suitable for carrying out the present invention is installed in a continuous casting mold, and numbers 1a and 1b in the figures are placed opposite to each other in the mold frame Mf. A pair of long side walls (hereinafter simply referred to as long side walls) of a water-cooled mold made of Cu are held fixed so that A pair of short side walls of the mold (hereinafter simply referred to as short side walls) are formed, and a continuous casting mold M is formed by the combination thereof. 3a and 3b are long side walls 1
These are magnetic poles for applying a static magnetic field that are arranged on the back surfaces of the molds 3a and 1b to control the flow of molten steel in the mold M, and these magnetic poles 3a and 3b consist of an iron core f and an electromagnetic coil c, which are connected to the long side wall 1a. , 1b is fixedly held within a mold frame Mf that holds the components. In addition, 4a and 4b are the short side walls 2a,
2b, and the width L of the continuous casting mold M is changed by moving each short side wall 2a, 2b along the width direction X of the long side wall by operating these devices 4a, 4b. 5 consists of a hydraulic cylinder or the like whose one end is swingably connected to the mold frame Mf of the long side wall 1b via a pin P as shown in FIG. 1, and whose other end is connected to another frame A of the continuous casting equipment. This clamping force relaxation mechanism 5 includes a clamping force conversion means 5a that converts the attraction force between the long side walls caused by the application of a static magnetic field into an increase in clamping force, and a clamping force conversion means 5a that converts the attraction force between the long side walls into an increase in clamping force. a clamping force addition means 5b that adds a preset clamping force (a clamping force sufficient to overcome the static pressure of molten steel) to the clamping force obtained, and a clamping unit that controls the clamping force based on the value obtained by the addition means 5b. A force control means 5c is provided, and in response to a command from the clamping force control means 5c, the long side wall 1b is pulled in the direction (Y direction) away from the other long side wall 1a, and the short side walls 2a and 2b are held together. Side wall 1a, 1
Relax the clamping force of b to an appropriate range. 6 is a tie rod that keeps the long side walls 1a and 1b at a predetermined distance, and 7 is a box that accommodates the coil S placed at the tip of the tie rod 6.The combination of the tie rod 6 and the box 7 that accommodates the coil S Long side wall 1a, 1
b is designed to have a clamping force that overcomes the static pressure of the molten steel supplied into the mold M. Further, 8 is a continuous casting immersion nozzle, and 9 is a guide roll arranged on the exit side of the continuous casting mold. In the continuous casting mold having the above configuration, the case is shown in which the clamping force relaxation mechanism 5 is provided only on one side of the long side wall 1b, but it can also be placed on the long side wall 1a side, and the number of installations is required. It can be increased accordingly.

[0006]

[Operation] When performing continuous casting of steel while applying a static magnetic field to the molten steel in the continuous casting mold M, as shown in FIG. As a result of the arranged magnetic poles 3a and 3b attracting each other, the long side walls 1a,
The short side walls 2a and 2b sandwiched between 1b are clamped with a force greater than the preset clamping force. The force F added at this time is F=B2/2×9.8×
μ0 (F: magnetic attraction force per unit area, B: magnetic flux density, μ0: magnetic permeability), and in this state, a very large force is required to move the short side walls 2a and 2b. Therefore, it was inevitable that scratches would occur on the surface of the long side walls when the short side walls 2a, 2b were moved.

In this invention, the relationship between the current value applied to the electromagnetic coils c of the magnetic poles 3a and 3b and the magnetic flux is determined in advance, and the influence of the force F is eliminated when the width L of the continuous casting mold M is changed. Since at least one of the long side walls 1a and 1b is pulled in the direction away from each other, scratches occur on the surfaces of the long side walls 1a and 1b even when the short side walls 2a and 2b are moved. This is not the case, and the force required to move the short side wall is not very large.

[0008]

[Example] 0.3T (Tesla) at magnetic poles 3a and 3b installed on the back of long side walls 1a and 1b of a continuous casting mold.
Continuous casting of slab strands with a thickness of 260 mm and a width of 1000 mm was carried out under the following conditions while applying a static magnetic field.
During the continuous casting operation, in order to change the mold width to 1200 mm, the long side wall 1b was heated to 4500 kgf, which is equivalent to the static pressure of molten steel.
650 by adding 2000 kgf of attraction force due to static magnetic field to
An operation was applied in which the long side walls were pulled apart from each other at approximately 0 kgf. As a result, the force required to move the short side wall was almost the same as when no static magnetic field was applied, and the resulting cast slab strand had no damage caused by scratches on the long side wall when the short side wall moved. No such deterioration of surface properties was observed, confirming that this invention is extremely effective.

[0009]

[Effects of the Invention] Thus, according to the present invention, when continuous casting is performed while controlling the flow of molten steel by applying a static magnetic field to the molten steel in the continuous casting mold, the operation of moving the short side wall of the mold is performed. Even in this process, there are no scratches on the long side walls of the mold, and continuous casting strands of good quality can be produced stably and with high efficiency.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of the configuration of a variable width continuous casting mold according to the present invention.

FIG. 2 is an explanatory diagram of the configuration of a variable width continuous casting mold according to the present invention.

FIG. 3 is an explanatory diagram of the configuration of a variable width continuous casting mold according to the present invention.

FIG. 4 is a diagram illustrating a situation in which the long side walls of a continuous casting mold are attracted to each other.

[Explanation of symbols]

1a Long side wall 1b Long side wall 2a Short side wall 2b Short side wall 3a Magnetic pole 3b Magnetic pole 4a Drive device 4b Drive device 5 Clamping force relaxation mechanism 6 Tie rod 7 Box 8 Immersion nozzle for continuous casting 9 Guide roll Mf mold frame f Iron core c Electromagnetic coil S Coil M Continuous casting mold

Claims (2)

[Claims] Claim 1: Continuous casting consisting of a pair of mold long side walls equipped with magnetic poles for applying a static magnetic field to control the flow of molten steel in the mold, and a pair of mold short side walls sandwiched between the mold long side walls. When performing continuous casting using a mold for continuous casting while applying a static magnetic field, pull at least one of the long walls of the mold in a direction away from each other to relieve the clamping force of the long walls of the mold that pinch the short walls of the mold, A method for changing mold width in continuous casting by applying a static magnetic field, characterized in that while maintaining this state, at least one of the short side walls of the mold is moved along the width direction of the long side walls of the mold. [Claim 2] A pair of long side walls of the mold arranged to face each other;
The mold has a mold formed by combining the long side walls of the mold with a pair of short side walls sandwiched between each other, and a static magnetic field for applying a static magnetic field to the back side of the long side walls of the mold to control the flow of molten steel in the mold. An apparatus for changing the mold width of a continuous casting mold, which is provided with a magnetic pole and includes a moving mechanism on at least one of the short side walls of the mold to move the short side wall of the mold along the width direction of the long side wall of the mold, is swingably connected via a pivot pin to a mold frame that holds the long side walls of the mold, and the other end is connected to a fixed frame of continuous casting equipment so that at least one of the long side walls of the mold is oriented away from each other. Equipped with a clamping force relaxation mechanism that relieves the clamping force that pinches the short side walls of the mold by pulling it to a clamping force conversion means for adding a preset clamping force to the clamping force converted by the clamping force conversion means; and a clamping force addition means for adding a preset clamping force to the clamping force converted by the clamping force conversion means; 1. A mold width changing device for continuous casting in which a static magnetic field is applied, characterized by comprising a clamping force control means for controlling the mold width.