JPH0871630A - Cooling method of high temperature metallic plate - Google Patents

Abstract

PURPOSE: To improve uniformity in the width direction of a material and to obtain a high quality product by moving a shield plate that shields cooling water in the direction of the arrow and thereby stepwise varying the shielding area by the shielding plate in each cooling zone in accordance with cooling conditions and the transporting speed of a metallic plate. CONSTITUTION: In this method, cooling water 6 is supplied from plural nozzles 5 arranged in the width direction of a high temp. metallic plate 1 that travels on a run out table, cooling the upper face or the lower face of the metallic plate 1. The means 2, which shields the cooling water 6 supplied directly to the end part in the width direction of the high temp. metallic plate 1, is arranged in plural numbers in the travelling direction inside a cooling zone; the area for shielding the cooling water is individually expanded/contracted in the width direction of the plate; and the cooling capacity is controlled in the width direction. Thus, a masking ratio is fixed for each shielding width of masking which is set in plural stages, the coiling temp. distribution is thereby obtained which is uniform in the width direction of the plate, and uniformity is improved in the width direction of the material.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to cooling a hot metal plate which is running.

[0002]

2. Description of the Related Art At a widthwise end portion of a high temperature metal plate, heat is radiated from side surfaces in addition to upper and lower surfaces, so that the temperature is lower than that at a central portion. If significant overcooling occurs at the edge of the metal plate, it becomes difficult to manufacture a product that is uniform in the width direction, which hinders quality improvement. In high-strength steel sheets, edge rupture called edge cracking occurs due to the temperature difference between the widthwise center and the edge (when the edge is lower, it is called edge overcooling) during cooling. There are also problems such as reduced product yield.

On the other hand, as disclosed in Japanese Patent Laid-Open No. 3-248709, there is a method of induction-heating the end portion of the sheet bar with an edge heater before finish rolling. Using this technology, finish rolling can be started in a state where the end supercooling is comparatively small, but since the end supercooling is reproduced again during the course of finish rolling, the metal plate can be used in the subsequent processes. A means for preventing end overcooling is required.

[0004]

On the other hand, in the runout table, as disclosed in Japanese Patent Laid-Open No. 59-24511, the cooling water directly supplied to the end of the metal plate is shielded to prevent the end supercooling. There was masking technology to prevent it. But,
Conventional masking has been performed empirically only to alleviate overcooling at the edges, and was not intended to make the temperature in the width direction of the metal plate uniform. Therefore, the shielding width in the zone for supplying the cooling water (hereinafter simply referred to as the cooling zone) has not been set by dividing it into fine parts.

FIG. 2 shows the temperature distribution at the edge of the metal plate before the start of cooling. In the figure, the horizontal axis is the distance from the end, and the vertical axis is the temperature. The temperature distribution at the end of the metal plate before the start of cooling is generally shoulder-shaped as shown by the curve 11 in FIG. From this, the distribution as shown by the curve 12 in FIG. 2 is obtained by cooling without masking. On the other hand, if masking is performed with the shield width 14 kept constant as in the conventional case, overcooling can be prevented to some extent at the outermost end of the metal plate, but the innermost portion of the shield is shielded more than necessary, and the curve 13 As described above, the uniformity of the temperature distribution in the width direction is rather disturbed.

[0006] By the way, the metal plate which is being conveyed may flutter or meander, but since the metal plate travels relatively stably after the tip is caught in the coiler, the rolling speed is increased from this timing to start the operation. I often do it. In such a case, in order to obtain a predetermined winding temperature, it is necessary to increase the number of cooling zones according to the transport speed of the metal plate and keep the time for cooling the metal plate being transported constant.

The present invention provides a method for cooling a high-temperature metal plate, which improves the deficiency of the conventional masking technique to make the temperature in the width direction uniform and can cope with changes in the transport speed of the high-temperature metal plate. The purpose is to provide.

[0008]

In order to solve the above problems, the present invention supplies cooling water from a plurality of nozzles arranged in the plate width direction of a high temperature metal plate traveling on a runout table, In a method of cooling a high temperature metal plate for cooling an upper surface or a lower surface of a metal plate, a plurality of means for shielding cooling water directly supplied to a plate width direction end portion of the high temperature metal plate are arranged in a running direction in a cooling zone, A high-temperature metal plate cooling method is characterized in that a range for shielding cooling water is individually expanded / contracted in the plate width direction to control the cooling capacity in the plate width direction. In this case, it is preferable to set the plate width direction expansion / contraction range that shields the cooling water in a plurality of stages, and according to the change in the transport speed of the metal plate passing through the inside of the cooling device, the length of the cooling zone in each stage and It is preferable to preset the range in the plate width direction of the means for shielding the cooling water so that the ratio with the length of the cooling water supply zone is constant. Furthermore, the plate width direction range of the shielding means may be changed so that the ratio of the length of the cooling zone and the length of the cooling water supply zone at each stage is made constant according to the change of the cooling water supply zone length. Is suitable.

[0009]

First, in FIG. 3, the end supercooling state of the metal plate at the start of cooling is represented by a modeled widthwise temperature distribution as represented by curve 22 in FIG. This modeling may be determined in advance by performing many measurements of the widthwise temperature distribution of the metal plate. For example, the width of the step of the curved line 22 is set every 50 mm from the end of the metal plate.

When the temperature distribution in the width direction at the start of cooling is given as the curve 22, in order to make the winding temperature constant in the width direction as shown by the curve 23, only the amount shown by the shaded portion in FIG. Cooling can be performed. At this time, the masking needs to be performed by changing the shielding width in each of the devices in a plurality of steps. The setting value of the shielding width may be determined by trial and error while measuring the widthwise distribution of the winding temperature for each steel type and plate thickness of the product, but it can also be obtained from a preset simple formula or the like. .

If the masking shield width is changed and set for each device in a plurality of steps, it becomes possible to control the temperature by finely dividing the metal plate in the width direction. As a result, the uniformity of the winding temperature in the width direction is dramatically improved, and the variation in the material between the central portion and the end portion of the metal plate is reduced. Further, it also has an effect of reducing the edge cutting margin and improving the product yield. By the way, generally, the temperature distribution in the width direction at the end of the metal plate hardly changes in the longitudinal direction. Therefore, the end supercooling to be corrected by masking may be constant in the longitudinal direction of the metal plate.

On the other hand, during the transportation of the metal plate, the length of the cooling zone may change with the speed of the metal plate. For example,
In the hot finish rolling mill, the speed of the metal plate being conveyed increases significantly after the tip of the metal plate is caught in the coiler. In that case, in order to make the cooling time of the metal plate constant, the cooling zone becomes longer in proportion to the increase of the metal plate speed. In such a case, the ratio of the masking shield zone length to the cooling zone length (hereinafter, simply referred to as the masking rate) must be constant, and the correction amount of end supercooling must also be constant.

FIG. 4 is an example of a diagram showing the relationship between the masking ratio obtained by model calculation and the end supercooling that can be corrected by masking. For example, when the supercooling at a certain control width is 40 ° C., if the masking is performed with a zone length of 50% of the cooling zone, the winding temperature at that portion becomes the same as the widthwise central portion. For that purpose, for example, when the cooling zone is 4 zones, masking may be performed in 2 zones, and when the cooling zone is 8 zones, masking may be performed in 4 zones.

The masking shield width in each device can be set by determining a fixed pattern so that the masking ratio remains substantially constant even if the cooling zone length changes. It is also possible to make the masking ratio constant by changing the pattern according to the change in the cooling zone length.

[0015]

EXAMPLE An example of the present invention will be shown in comparison with the conventional technique for setting the masking shield width in the case where the cooling zone changes from 4 zones to 8 zones during conveyance of a metal plate. FIG. 1 is a schematic plan view of a shield plate for explaining an embodiment of the present invention. The masking device is for each cooling zone No. 1 to N
o. One is installed in 8 each. FIG. 5 is a view on arrow AA of FIG. In FIG. 5, the cooling water 6 is supplied to the high temperature metal plate 1 running on the table roller 10 from the nozzle 5 provided in the header 4. The shield plate 2 that shields this cooling water is moved by the motor 7 and the guide shaft 8 as shown by an arrow 9.

First, the temperature distribution at the edge of the metal plate at the start of cooling was modeled as a curve 22 in FIG. Table 1 shows the edge overcooling at this time and the optimum value of the masking ratio obtained by the model calculation. 0 to 50 from the width of the metal plate
mm part (edge 0 to 50 mm) and a part 50 to 100 mm from the plate width end of the metal plate (edge 50 to 10).
(0 mm), since the end supercooling is different, the appropriate values of the masking ratio also differ from 50% and 25%.

Tables 2 to 4 compare the masking shield width setting patterns between the conventional example and the embodiment of the present invention. Further, Table 5 shows the temperature at each position in the width direction when the winding temperature was 550 ° C., for each example. Table 2
Is a conventional masking masking width setting pattern. Case 1 is a cooling zone No. 1-No. When No. 4 is used, Case 2 has cooling zone No. 1-No. This is the case when 8 is used. In Table 2 (comparative example), masking with a shielding width of 100 mm is performed for all odd-numbered zones. At this time, the winding temperature was the same as that in the center in the width direction because the masking was performed at an appropriate ratio in the portion of the edge 0 to 50 mm. However, the winding temperature was higher than the center in the width direction by 20 ° C. because the masking ratio was too higher than the proper value in the edge portion of 50 to 100 mm. Although overcooling at the edges could be prevented by masking, the widthwise distribution of the winding temperature was not uniform, so there was a limit to obtaining a uniform material in the widthwise direction, and high quality products could not be manufactured.

Table 3 is a first example of a masking shield width setting pattern according to the present invention. Case 1 and case 2 are the same as in Table 2. In Table 3, the masking shield width in each device is determined so that the masking ratio remains substantially constant even if the cooling zone length changes, and the shield width is not changed during the transportation of the metal plate. When there are 4 cooling zones (Case 1)
The masking ratio is 50 at the edge of 0 to 50 mm.
%, And 25% at the edges of 50 to 100 mm, and as shown in Table 1, they could all be made equal to the proper values. Further, the masking ratio when the number of cooling zones was 8 (case 2) was also able to be made equal to the appropriate value. As a result, not only was it possible to prevent overcooling of the edges of the metal plate, but it was also possible to dramatically improve the winding temperature, and thus the width-wise uniformity of the material, compared with the conventional technology, and to improve the quality. It was possible to manufacture high quality products. In addition,
Even when the cooling zone is changing from 4 zones to 8 zones, that is, when the cooling zones are 5 to 7 zones, the masking ratio only slightly increases or decreases to a value close to an appropriate value, so the widthwise distribution of the winding temperature is the entire coil. It was possible to make it almost uniform over the entire length.

Table 4 shows a second example of the masking shield width setting pattern according to the present invention, and Case 1 and Case 2 are the same as Table 2. FIG. 1 is a diagram schematically showing changes in the setting pattern. In this pattern, edges 0-5
In order to keep the masking ratio at 0 mm and the edge 50 to 100 mm always close to an appropriate value, the masking shield width in each device is changed according to the change in the cooling zone length. For example, in case 1, No. 3 to No. The shielding plates 2 in the four zones are located at the position 2a, and in the case 2 are located at the positions 2b, respectively, so that the masking ratio is kept constant.

The masking ratio when the cooling zone is 4 zones (case 1) and when it is 8 zones (case 2) is 50 at the edge 0 to 50 mm portion as in the first embodiment of the present invention.
%, And 25% at the edges of 50 to 100 mm.
In each case, the values can be made equal to the appropriate values shown in Table 1, and the same effects as the first example of the present invention could be obtained. As the cooling zone changes from 4 zones to 8 zones, the masking shield width is changed from pattern A (case 1) to pattern B (case 2) in Table 4. Therefore, even when the cooling zone is 5 to 7 zones, the masking ratio can be maintained at a value close to an appropriate value, and the widthwise distribution of the winding temperature can be made substantially uniform over the entire coil.

[0021]

[Table 1]

[0022]

[Table 2]

[0023]

[Table 3]

[0024]

[Table 4]

[0025]

[Table 5]

[0026]

As described above, according to the present invention, a uniform winding temperature distribution is obtained in the width direction of the metal plate by keeping the masking ratio constant for each of the masking shielding widths set in a plurality of stages. I was able to. As a result, the uniformity of the material in the width direction was dramatically improved as compared with the conventional technique, and a high quality product could be manufactured. Although the masking masking width is set in two steps in this embodiment, the present invention is not limited to this, and the masking width may be set in three or more steps.

[Brief description of drawings]

FIG. 1 is a schematic plan view showing the operation of a shielding plate according to an embodiment.

FIG. 2 is a schematic graph illustrating a temperature distribution at an end portion of a high temperature metal plate.

FIG. 3 is a graph showing a temperature distribution at an end portion of a metal plate illustrating an example.

FIG. 4 is a graph showing a relationship between an end supercooling correction amount and a masking ratio.

5 is a view on arrow AA in FIG. 1. FIG.

[Explanation of symbols]

 1 Metal Plate 2 Shielding Plate 3 Moving Direction 4 Header 5 Nozzle 6 Cooling Water 7 Motor 8 Guide Shaft 9 Arrow 10 Table Roller 11, 12, 13 Curve 21, 22, 23 Curve

 ─────────────────────────────────────────────────── ─── Continued front page (72) Inventor Ichiro Maeda 1 Kawasaki-cho, Chuo-ku, Chiba City Kawasaki Steel Co., Ltd. Steel Development & Production Division Chiba Steel Works (72) Inventor Hidetaka Takemura 1 Kawasaki-cho, Chuo-ku, Chiba City Kawasaki Steelmaking Co., Ltd. Steel Development & Production Division Chiba Steel Works

Claims (4)

[Claims] 1. A high-temperature metal plate cooling method, wherein cooling water is supplied from a plurality of nozzles arranged in the plate width direction of a high-temperature metal plate traveling on a runout table to cool the upper surface or the lower surface of the metal plate. A plurality of means for shielding the cooling water directly supplied to the end of the metal plate in the plate width direction are arranged in the running direction in the cooling zone, and the range for shielding the cooling water is individually expanded / contracted in the plate width direction. A method for cooling a high-temperature metal plate, which comprises controlling the cooling capacity in a direction. 2. The method for cooling a high temperature metal plate according to claim 1, wherein the expansion / contraction range in the plate width direction of the means for shielding the cooling water is set in a plurality of stages. 3. The cooling water so that the ratio of the length of the cooling zone and the length of the cooling water supply zone at each stage is made constant according to the change of the transport speed of the metal plate passing through the inside of the cooling device. The method for cooling a high temperature metal plate according to claim 2, wherein the range of the plate width direction of the means for shielding is preset. 4. According to the change of the cooling water supply zone length,
3. The high temperature metal plate according to claim 2, wherein the range of the shielding means in the plate width direction is changed so that the ratio of the length of the cooling zone and the length of the cooling water supply zone at each stage is kept constant. Cooling method.