JPH03189056A - Method for controlling dummy bar head for continuous casting - Google Patents

Abstract

PURPOSE:To prevent bending of a cast slab caused by defective separation by discriminating defective shape of dovetailing part at tip part of a dummy bar head under using electric current value for hanging up the dummy bar as reference at the time of separating the dummy bar head from the cast slab. CONSTITUTION:The separation of dummy bar 3 is executed with rotation along inner and outer circumferential faces A, B in the dovetailing part 2b. The electric current value is raised according to separation rotating angle of the dummy bar 3 and the peak value thereof is developed at 70 - 90 deg. angle. In the case of using 1.0 for the max. load current value at the ordinary time, when the load current value becomes more than 2.0, the cast slab is drastically deformed and the trouble is developed. By controlling pattern of the current value and the peak value thereof at the time of separating the dummy bar head from the cast slab, trouble of checking gage and visual examination can be eliminated, and early repairing and disposal treatment can be normalized.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for managing dummy bar heads in continuous casting.

(Prior Art) In continuous casting, a method is adopted in which molten steel in a mold is sealed with a dummy bar head, and a solidified slab is coupled to the dummy bar head and guided through a slab support device.

Various methods have been proposed for joining this slab and the dummy bar head, and one of the representative ones is the 52nd Utility Model.
As shown in Japanese Patent No. 14736, there is a dummy bar head which has a dovetail portion at the tip and uses a 7-foot bar that can move up and down and a lifting machine.

In addition, as shown in FIG. 4, dovetail portions 2a, 2
There is also a method in which the dummy bar head 3 is connected via the dummy bar head 3, and after being guided through the slab supporting device, the dummy bar head is separated by a crane or a hoisting mechanism using a winding drum. This method requires simple equipment and does not require complicated labor.

(Problem to be solved by the invention) However, in the case of this combination of alar parts, PIS
As shown in Figure 4, the trajectory at the time of separation shifts from symbol O to ■, and the trajectory until section 0 of the dummy bar head 3 passes through the 7-ribbed section 2a of the slab 1 is along the A plane. , After the dummy bar head 3 has come off, the D part of the dummy bar head 3 moves down along the B side of the slab 1, and the locus changes greatly and is separated and becomes %1. Therefore, it is naturally important to measure the shape of the dovetail portion, and we perform visual inspections of deformation, wear, etc., and measurements using an alpha tester, and those that exceed a predetermined value are buried again.

However, since the deformation and wear of this dummy bar head are complicated, even if the inspection data measurement results of the outer shape and dovetail portion are good, the dummy bar head cannot be separated, resulting in damage to the equipment and interruption of continuous casting operations.

In addition, in order to prevent these situations and perform normal continuous operation, it is necessary to repair or discard the rad on the dummy bar at an early stage.

(Means for Solving the Problems) The present invention provides a method for connecting and guiding a slab to the tip of a dummy bar head via a dovetail portion, lifting the dummy bar at the end of a continuous casting machine, and separating the dummy bar head from the slab. A method for managing a dummy bar head for continuous casting, characterized in that a defective shape of a dovetail portion at the tip of the dummy bar head is determined based on the point in time when the lifting current value of the dummy bar becomes more than twice the normal maximum load current value. be.

(Function) The inventors of the present invention found that no matter how much defective products are determined by visual judgment and inspection data in order to understand the deformation and wear of the dummy bar head, some of the passed products become detached and become defective. Furthermore, we have learned that this differs depending on the casting type, the dummy bar cooler's bite, the temperature of the slab, etc., and that if the dummy bar head and slab are separated with more than a predetermined force, the slab surface will warp. Furthermore, as a result of various studies based on these findings, we found that even if the dummy bar head conforms to the shape, it is difficult to centrally manage the casting type, conditions, etc. It has been found that the variation closely approximates the quality of gummy bar heads. The present invention has been made based on this knowledge.

The separation of the dummy bar head involves rotation along the inner and outer circumferential surfaces A and B of the 7-ribbon part 2b as shown in Fig. 4, and when this is shown in Fig. 1, the separation rotation angle of the gummy bar head is Therefore, the current value increases sequentially and reaches a peak value between 70 and 90 degrees.

As shown in FIG. 2, if this load current value exceeds 2.0, assuming that the maximum load current value under normal conditions is 1.0, the slab will be significantly deformed and problems will suddenly occur.

In this way, when the dovetail portion at the tip of the dummy bar head is separated from the slab, it always shows the current peak value shown in Figure 1, and this current peak value indicates the true difficulty of separating the dummy bar head from the slab. It reflects. That is, as long as this peak value is within a predetermined value, even if the peak value changes slightly, a large bending force will not be applied to the hot slab, and the continuous casting equipment will not be damaged or the casting operation will be interrupted. As shown in Figure 2, this current peak value should be set to a current index value of 2.0 or less, preferably 1.5 or less, so as to prevent not only the shape of the dummy bar head but also the operating conditions and operation history of the dummy bar. It is possible to determine whether the product is good or bad, and the reproducibility and accuracy are extremely high.

In this way, by managing the current value pattern and its peak value when the gummy bar head and slab are separated, the effort of inspection and visual inspection can be omitted, and early repair and disposal can be normalized. .

(Example) An example of the method of the present invention based on current value discrimination and a comparative example based on conventional visual inspection and inspection data were compared using a dummy bar size of 88
Figure 3 shows the results of comparison using 13 sets of 0 to 1475 m-. As is clear from FIG. 3, the method of the present invention is extremely superior in that there is no casting trouble and the life of the dummy bar head can be approximately doubled.

(Effects of the Invention) As described above, the method of the present invention makes it possible to properly manage the dummy bar head, and prevents the surface of the slab due to poor separation.
It is possible to prevent damage to equipment such as tethering attachments and cranes, and interruption of i# post-work due to these. Furthermore, it is possible to quickly repair and dispose of the dummy bar head properly, and the life of the dummy bar head can be extended while reducing the number of accidents, which is extremely excellent.

[Brief explanation of drawings]

Figure 1 is a diagram showing the current change pattern when separating the dummy bar head, vJ2 diagram is a diagram showing the current value index, the amount of deformation of the slab, and its critical point, Figure 3 is a diagram showing the results of the example, FIG. 4 is a diagram showing the separation locus of the gummy bar head and slab. 1... Slab, 2a, 2b... Arizan part, 3...
dummy bar head.

Claims (1)

[Claims] (1) When connecting and guiding the slab to the tip of the dummy bar head via the dovetail part, lifting the dummy bar at the end of the continuous casting machine, and separating the dummy bar head from the slab, the lifting current value of the dummy bar should be lower than the normal value. A method for managing a dummy bar head for continuous casting, characterized in that a defective shape of a dovetail portion at the tip of the dummy bar head is determined based on the point in time when the current value exceeds twice the maximum load current value.