JPS6049049B2 - Method for preventing vertical bending of shaped steel by water cooling - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for appropriately preventing vertical bending of a section steel caused by water cooling.

It is well known that H-shaped steel and other shaped steel are cooled after rolling, but the products that have been cooled tend to have upward bends as shown in Figure 1A and downward bends as shown at the bottom. There is.

These vertical bends in steel sections are generally corrected using a roller straightening machine, but if the required straightness cannot be obtained, a separate press straightening machine is used to straighten them, which is a tedious process. is taken. In addition, when the roller straightening machine rolls down the web surface with the upper and lower straightening rollers that are generally arranged in a staggered manner, excessive stress is applied to the web surface, causing cracks in the corners (fillet portions) of the web and the flange. There were cases where this occurred. The present invention was proposed as a result of various experiments and studies to address this current situation. In other words, the present invention predicts in advance the amount of vertical bending of the shaped steel due to the sawing pattern, and controls the water cooling position of the shaped steel flange surface in the vertical direction according to this predicted bending amount, thereby reducing the vertical bending of the shaped steel. Its basic feature is to provide appropriate prevention. Next, specific examples of the present invention will be described.

The present inventors first conducted a detailed study on the tendency for vertical bending to occur in the cooling bed of H-beam steel. That is,
When we investigated the relationship between the sawing pattern of material that had not been used in a water cooling device (by simply allowing it to cool) in the cooling process and the vertical bending pattern after cooling, the results shown in Table 1 were obtained. Note that the sawing patterns (ANB, , C) in this table are as follows. A: Long length (several phrases) Ten short length (several phrases) B: Same length (
Several phrases) Ten long shaku (last one cut) C: Same length (several phrases) Ten short shaku (last one cut) Also, vertical bend pattern (I) ■, ■)
is as shown in FIG.

Table 1 (numbers indicate the frequency of occurrence of each vertical bending pattern) In this way, the tendency of vertical bending after cooling of unwater-cooled material is as follows:
It can be understood that the cutting pattern differs depending on the sawing pattern with the hot saw, and there is a correlation as shown in the table above.

This is thought to be due to the difference in temperature between the top and bottom of the flange during rolling and the thermal influence of adjacent materials on the cooling bed. Therefore, once the sawing pattern with a hot saw is determined, the vertical bending pattern of the steel material after cooling without water cooling can be predicted. On the other hand, according to research by the present inventors, when the flange surface of an H-beam steel is water-cooled in the cooling process, the bending direction of the H-beam steel changes depending on the water-cooling position. It was found that this phenomenon becomes more noticeable as one approaches the end of the direction.

FIG. 3 shows an example of the experiment. As shown in the figure, once the speed of the material passing through the water cooling zone (table speed) and the nozzle position are determined, the amount of vertical bending of the section steel can be determined. In other words, when the material speed is constant, it can be seen that when the lower end of the flange surface is cooled, the section steel curves upward, and when the upper end is cooled, it curves downward (note that the nozzle position in Figure 3 is the same as in Figure 5). (This is the height from the bottom edge of the section steel flange surface as shown in Figure 1). Therefore, for example, the fourth
As shown in the figure, the bending of the unwater-cooled section steel after cooling is such that the first cut a on the top side is a large downward bend, and then the second cut b, the third cut c, and the fourth cut d change to an upward bending direction. As shown by the arrow in the same figure, the lower part of the flange surface is water-cooled at the first cut a, and as the water-cooling position is raised toward the bottom, the vertical bending of the section steel is eliminated. It becomes. 3. Therefore, in the present invention, headers 2, 2 for water-cooling both flange surfaces 1, 1 of the section steel are installed movably up and down on the front or rear surface of the finishing rolling mill, as shown in FIG. The height of the water cooling headers 2, 2 is adjusted according to the water cooling pattern. In other words, the present invention determines the hot saw sawing pattern from the unrolled billet weight content and the sawing remaining order content, predicts the amount of vertical bending in accordance with the hot saw sawing pattern, and uses the predicted bending amount to water-cool the material. The pattern, that is, the height of the water-cooled header on the top side of the shaped steel and the water-cooled position of the entire length are determined, and the water-cooled header is raised and lowered according to the commands. According to the present invention as described above, in order to prevent vertical bending of a shaped steel, the amount of vertical bending of the shaped steel due to the sawing pattern is predicted in advance, and the flange surface of the shaped steel is adjusted according to the predicted amount of bending. Since there is a device that adjusts the water cooling position in the vertical direction, vertical bending due to water cooling after rolling can be properly prevented, and even if vertical bending occurs, it is slight, and therefore it can be sufficiently corrected with a roller straightening machine. Moreover, since no large stress is applied to the web surface, various advantages such as no cracking at the corner with the flange surface can be obtained.

[Brief explanation of the drawing]

Figure 1 is a state diagram of the vertical bending of the shaped steel caused by water cooling, A shows the upward bending state and the downward bending state, and Figure 2 shows the vertical bending pattern of the shaped steel in Table 2. FIG. 3 is a graph showing the vertical bending variation of the section steel due to changes in nozzle position, FIG. 4 is a graph showing an example of the water cooling pattern in the present invention, and FIG. 5 is a graph showing the water cooling pattern in the present invention. It is a schematic diagram showing an example of a nozzle. In the figure, 1 is a flange surface, and 2 is a water cooling header.

Claims (1)

[Claims] 1. In preventing vertical bending of H-shaped steel and other shaped steel,
A method for preventing vertical bending of a shaped steel by water cooling, characterized in that the amount of vertical bending of the shaped steel due to a sawing pattern is predicted in advance, and the water cooling position of the flange surface of the shaped steel is adjusted in the vertical direction according to the predicted amount of bending.