JPS6341670B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a stirring device for crater ends of continuously cast slabs.

In recent years, electromagnetic stirring devices have been widely introduced into continuous casting equipment, contributing to improving the quality of slabs. 2
Application in the secondary cooling zone has a clear effect on improving the solidified structure, especially increasing the equiaxed crystallinity, but it is generally still not sufficient to improve the solidified structure in the center, such as center segregation and center porosity. It cannot be said that it is at a practical level. This is because the thickness of the solidified shell is large during stirring at the final stage of solidification, which reduces the effective electromagnetic force on the internal molten steel, and the liquid core inside the slab is small, making it difficult to cause flow, which are negative factors for the stirring action. However, a major problem is that the stirring position at the final stage of solidification is not appropriate.

That is, there is an appropriate timing for stirring at the final stage of solidification; if it is too early, the stirring force will not reach the crater end, leaving segregation and porosity in the center. Moreover, if it is too slow, the remaining molten steel will thicken, and the fluidity of the molten steel will deteriorate, resulting in insufficient stirring and poor mixing with the surrounding hot water, which has not yet thickened, so that the central structure will not be improved in this case as well. Appropriate stirring timing varies somewhat depending on the steel type, but generally the diameter of the liquid core of residual molten steel is in the range of several tens of millimeters.

On the other hand, an electromagnetic stirring device (hereinafter abbreviated as EMS) is usually fixedly installed inside the roller apron (slab guide device) of continuous casting equipment. However, since the final solidification position of a slab varies depending on casting speed, cooling conditions, steel type, etc., if the EMS is fixed, the stirring position cannot be returned to the previous appropriate position under all casting conditions.

Therefore, it is an object of the present invention to provide a stirring device for a crater end of a continuous cast slab, which can always stir the slab at an appropriate position under all casting conditions.

The structure of the present invention will be explained in detail based on the embodiment shown in the drawings. As shown in FIG. Next, a pinch roll 7 is installed, and roller tables 8 and 9 are installed in front of the pinch roll 7.

In the above profile, the EMS body 10 is placed in the casting direction of the segments 5 and 6 near the pinch roll 7.
The EMS main body 10' is movably installed in the slab drawing direction of the roller tables 8 and 9, respectively.

The movement mechanism of the EMS main body 10 will be explained based on FIGS. 2 and 4.
Lower frames 14, 14' are installed above so as to be parallel to the moving direction of the slab 13, and two support columns 15,
15, 15', 15', and upper frame 1
6 and 16' are supported so that they can be raised and lowered. A plurality of lower rolls 17, . . . are supported on the upper surfaces of the lower frames 14, 14' on both sides, and the upper frames 16,
The upper rolls 18 facing the lower roll 17 are supported on the lower surface of the roll 16'.

In addition, rails 20, 20' are fixed to support parts 19, 19' protruding from the opposite sides of the upper frames 16, 16', and wheels 21,
The EMS main body 10 is made to run by riding on...

Also, support rods 22, 22' are fixed across both ends of the upper frames 16, 16' on both sides, and both support rods 2
Two guide rods 23, 23' are fixed across the two guide rods 23, 22', and a plurality of hooks 24, . Power supply cable 2 installed between
He is hooking 6,26'.

A similar mechanism is installed on the foundation 12 where the segment 6 is located, and the rails 20 and 20' are connected so that the EMS main body 10 can be moved across the segments 5 and 6.

Reference numeral 27 in FIG. 4 is a fluid mechanism for raising and lowering the upper frames 16, 16' relative to the supports 15, 15'.

Next, the moving mechanism of the EMS main body 10' will be explained based on FIGS. 3 and 5. The table rolls 28, . . . of the roller table 8 are supported by mount frames 29, 29' provided on the foundation 12. Rails 20, 20' are provided on both sides of the table rolls 28,...
are installed, and wheels 21, . . . attached to a mobile cart 30 are mounted on rails 20, 20' on both sides.
A through hole 31' is provided in the center of the upper wall 31 of this moving cart 30.
A part of the EMS main body 10' is made to protrude from the through hole 32, and the EMS main body 10' is fixed to the upper wall 31 by an L-shaped mounting member 31' with a bolt 33. still,
Adjustment of the slab 13 in the height direction is performed by inserting a liner between the mounting member 32 and the upper wall 31.

In addition, the power supply cables 26, 26' are connected to the mobile cart 30.
A cable carrier 33' is connected to the relay boxes 25' between the relay boxes 25' attached to the sides of the cable carrier 33', and this cable carrier 33' is supported by a pedestal 34 as shown in FIG. And cable bear 3
A relay box 25'' is attached to the other end of 3'.

35 in FIG. 5 is a cable carrier.

Note that the roller table 9 also has rails 20,
Install 20'.

The present invention is configured as described above, detects the crater end according to the operating conditions, and based on this detects the crater end.
Determine the optimal position of the EMS main body 10, 10'. The following method is used as a means for this purpose.

(1) Detect the crater end, back estimate the solidified shell production rate from that position, find the liquid core position where the stirring effect is maximum, and position either the EMS main body 10 or 10' at that position.

Direct detection of the crater end is quite difficult with current technology, but one method that can be applied with current technology is to detect the surface temperature of the slab and estimate it based on the change. This takes advantage of the fact that when the liquid core disappears after passing the crater end, the latent heat of solidification disappears and the amount of drop in surface temperature of the slab suddenly increases.

(2) Using the method described above, grasp the positional relationship between the operating conditions and the optimal stirring position in advance based on the operating results, and before starting the operation,
0' is set in that position and remains fixed during operation.

By using the method (1), it is possible to respond to various changes in casting conditions during operation, so more reliable effects can be obtained. Although the method (2) cannot respond to changes during operation, it does not require real-time position control of the EMS bodies 10, 10', so the equipment cost is low.

The present invention has the above-mentioned structure and function, and since the EMS is movable, (1) Even if the casting conditions change, stirring can always be performed at the optimum position, so that all the target slabs can be stirred. On the other hand, electromagnetic stirring can be expected to improve quality.

(2) Depending on the equipment to be applied, if you want to reduce equipment costs, the EMS can be fixedly installed for each casting condition, so it has a wide range of applications.

(3) Since the slab can be supported and stirred by the upper roll, there is no risk of bulging occurring.

[Brief explanation of the drawing]

The figures show an embodiment of the stirring device for crater ends of continuously cast slabs according to the present invention, in which Fig. 1 is a side view, Fig. 2 is a front view taken along the line - in Fig. 1,
Figure 3 is a front view seen from the - line in Figure 1;
The figure is a sectional view taken along the line - - in Fig. 2, and Fig. 5 is a front view taken from the line - - in Fig. 3.

Claims (1)

[Claims] 1 A roller apron segment, a pinch roll, and a roller table are arranged close to each other in sequence in the flow direction of the slab, and two lower frames supporting a plurality of lower rolls are placed on the foundation where the roller apron segment is located. An upper frame having a plurality of upper rolls facing the lower roll is provided above both lower frames and arranged in parallel along the drawing direction, and rails are arranged on each of the upper frames to form the main body of the electromagnetic stirring device. is movably mounted on the roller table, and a portal-shaped movable trolley on which the electromagnetic stirring device main body is mounted is movably mounted on the roller table with rails arranged parallel to the slab drawing direction. A stirring device for crater ends of continuously cast slabs.