JPS6256930B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a cooling control method for hot-rolled steel sheets, and in particular, to prevent excessive temperature drop at the side edge portions of hot-rolled steel sheets by blocking plates for cooling water spray disposed along both sides of a conveyance line for hot-rolled steel sheets. The present invention relates to a method for controlling cooling of a hot rolled steel sheet. A hot rolled steel sheet taken out from a continuous hot rolling mill is cooled by cooling water spray on a cooling table (conveyance line) to a predetermined winding temperature before being wound up in a winding machine. Generally, each side edge portion of a steel plate to be rolled has a larger temperature drop during rolling and a larger cooling rate during cooling than the center portion of the sheet width, so the winding temperature is lower at each side edge portion as shown in Figure 1. At 30℃~60℃ compared to the central part
℃, and if left as is, problems such as shape defects due to the difference in thermal shrinkage in the width direction X and poor flatness as a pipe material due to non-uniformity of the material in the width direction X will occur. To solve this problem, as shown in FIG. 2, each side edge portion 1 of the hot rolled steel sheet 10 is
From 0a, 10b toward the central part 10c of the board width,
A large number of blocking plates 12 having a predetermined blocking width W are provided along both sides of the cooling table 14, and the blocking plates 12 of each bank are arranged as shown in FIG. 2C to isolate that portion from the cooling water. Thus, a cooling control method is known in which an excessive temperature drop in the side edge portions 10a, 10b is gradually and strongly prevented as the side edges are approached. Each shield plate 12 includes a hot rolled steel plate 1
They are fixed symmetrically with respect to the center of the cooling table 14 on the premise that 0 is conveyed through the central portion of the cooling table 14. In addition, 16 is a finishing rolling machine, 18 is a table roller, 20 is a winding machine,
22a and 22b are upper and lower cooling headers. However, in reality, the width direction of the hot rolled steel sheet
Due to uneven plate thickness, inclination of the cooling table 14, etc., the hot-rolled steel sheet 10 does not pass through the center of the cooling table 14, especially at the leading end (tip) and tail end (rear end). It is conveyed biased to either the left or the right. For this reason, the conventional cooling control method can only be used during a stable conveyance state from when the leading end of the hot rolled steel sheet 10 is taken up by the winder until the tail end passes through the finishing stand. , even 50 in between
There was a meandering of ~100 mm, making it difficult to accurately cut off the predetermined cutoff width W. If the cooling water at the side edge portions 10a, 10b is not shut off accurately in the width direction There is also a risk that it may worsen. The present invention has been made in view of these problems, and an object of the present invention is to provide a cooling control method that can always cut off a side edge portion of a predetermined width regardless of the meandering of a hot rolled steel sheet. . The present invention provides a cooling control method for hot-rolled steel plates, in which the conveyance position of the hot-rolled steel plate is detected online by a position detection sensor in the width direction of the hot-rolled steel plate provided along the conveyance line, and the detected value is The above object is achieved by moving the blocking plate in the width direction of the hot-rolled steel plate in response to the problem, and correctly blocking the side edge portion from the cooling water spray by a predetermined blocking width. FIG. 3 shows a cooling device for hot-rolled steel sheets in which the method of the present invention is adopted. To explain the configuration, a cooling table 1 is installed between the finishing rolling mill 160 and the winding machine 200.
40, an upper cooling header 220a is installed at a predetermined height on the upper part of this cooling table 140, and a lower cooling header 220b is installed on the lower part. As shown in FIG. 3B, the upper cooling header 220a is provided with a large number of cooling water nozzles 221a facing downward arranged at predetermined intervals in the width direction X of the hot rolled steel plate 100, and similarly the lower cooling header 220a
b is provided with a large number of cooling water nozzles 221b facing upward. Each cooling table 140
Cooling water is injected onto the upper and lower surfaces of the hot rolled steel sheet 100 above. Further, for the upper cooling water header 220a, the upper shielding plate 120a is the same, and for the lower cooling water header 220b, the lower shielding plate 1 is
20b are provided respectively. The upper and lower blocking plates 12
0a, 120b are both side edge portions 100a, 100
Motors 300a, 300 provided separately for b
b can be moved independently or simultaneously in the width direction X, and the cut-off width W of the cooling water injected from the upper and lower cooling water headers 220a, 220b onto both the upper and lower surfaces of the hot rolled steel sheet 100 can be changed. and 4
00 is a sensor for detecting the position of the hot rolled steel sheet 100 in the width direction X. The method of the present invention uses this sensor 400 to detect online the width direction position of the hot rolled steel plate 100 at the detection position, that is, the conveyance position, and
The value obtained by subtracting the specific cutoff width determined for each bank from the signal shown in Table 1, for example, is
The calculator 500 calculates this value, and uses this value as the displacement position to which the blocking plates 120a, 120b in each bank should be moved, and the motors 300a, 300b are moved by that amount.
, and controls the position of each blocking plate 120a, 120b.

[Table] As a result, as shown in FIGS. 3C and 4, even if the hot rolled steel sheet 100 meanders, the shielding plates 120a and 120b are always set following the same direction. The edge portion is correctly blocked from the cooling water spray by a predetermined blocking width W. Note that the position detection sensor 400 in the width direction
In view of the harsh environment of hot rolling mills, from the viewpoint of reliability, a water flow type sensor (Jikkosho 52 -25175) is preferred, but any sensor that can detect where the hot rolled steel sheet 100 is on the cooling table 140 may be used, such as a magnetic sensor. Note that in the illustrated embodiment, the cooling table 140
Water flow type width direction position detection sensor 40 at two locations on the top
0 is installed to implement this cooling control method,
The sensor 400 is not limited to two locations. Furthermore, since there is almost no meandering immediately after exiting the finishing mill 160, the apparatus may be simplified by using a fixed type. Furthermore, regarding the motors 300a and 300b, instead of providing four separate motors in total, one or two motors are provided, and each shield plate 120a, 120b is provided separately.
It goes without saying that these may be interlocked by appropriate mechanical means. FIG. 6 shows the widthwise distribution of the coiling temperature of the hot rolled steel sheet when cooled by the method of the present invention, and
FIG. 7 shows the widthwise distribution of the winding temperature when the cooling water is simply shut off symmetrically around the center of the table as in the prior art. In both figures, A indicates the leading end portion of the hot rolled steel plate, and B indicates the relatively stable central portion. The plate width was 1200 mm, the finishing temperature was 850°C, the winding temperature was 550°C, and the cutoff widths were both values as shown in Table 1 above. This distribution diagram shows that when cooling is performed using the conventional method, as shown in Figure 7, not only is the temperature distribution in the width direction not uniform due to the large meandering at the leading end, but the temperature distribution is at the middle bulge, and the center Due to the meandering of the hot-rolled steel sheet, the temperature distribution is slightly higher at the side edges, but when cooled by the method of the present invention, as shown in Fig. 6, despite the meandering of the hot-rolled steel sheet, It can be seen that the temperature distribution is uniform in both the leading end and the center. As described above, according to the present invention, regardless of the meandering of the hot-rolled steel sheet, it is possible to always correctly cut off the cooling water spray only by a predetermined cutoff width. This effect is particularly remarkable in the leading end and tail end portions of the hot rolled steel sheet where the degree of meandering is large. As a result, product quality has improved, especially shape improvement and material uniformity to a higher degree.
Moreover, it is possible to obtain the effect that the process can be carried out with a high yield.

[Brief explanation of the drawing]

Figure 1 is a temperature distribution diagram in the width direction of a hot-rolled steel sheet showing a cooling characteristic diagram when no particular cooling control is applied;
Figures A, B, and C are explanatory diagrams, including partial block diagrams, of a cooling device that employs a conventional cooling control method for hot-rolled steel sheets, where A is a front view, B is a side view, and C is a plan view. , Fig. 3 A, B, and C are views corresponding to Fig. 2 A, B, and C in which the hot-rolled steel plate cooling control method according to the present invention is adopted, and Fig. 4 shows a case where the shield plate is a meandering part of the hot-rolled steel plate. Figure 3 B corresponds to the state following the figure 5 A, B
6A and 6B are explanatory diagrams showing an example of a position detection sensor, A is a front view, B is a side view, and FIGS. 6A and 6B are width direction temperature distribution diagrams of a hot rolled steel plate cooled by the present invention,
A shows the leading end part, B shows the central part, and FIGS. 7A and 7B show the temperature distribution in the width direction of a hot rolled steel plate cooled by the conventional method in comparison with that according to the present invention. This is a distribution map corresponding to FIGS. 6A and 6B. 10,100...hot rolled steel plate, 10a, 10b,
100a, 100b...side edge portion, 22a, 22
0a... Upper cooling header, 22b, 220b...
Lower cooling header, 400...Position detection sensor, X
...Width direction of the hot rolled steel plate, W...Predetermined cut-off width.

Claims (1)

[Scope of Claims] 1. A hot-rolled steel sheet in which an excessive drop in temperature at the side edge portions of the hot-rolled steel sheet is prevented by shielding plates for cooling water spray disposed along both sides of a hot-rolled steel sheet conveyance line. In the cooling control method, the conveyance position of the hot rolled steel plate is detected online by a position detection sensor in the width direction of the hot rolled steel plate provided along the conveyance line, and the shielding plate is heated according to the detected value. 1. A cooling control method for a hot rolled steel sheet, comprising: moving the rolled steel sheet in the width direction, and correctly blocking the side edge portion from cooling water spray by a predetermined blocking width.