JP2010064117A - Method for manufacturing hot-rolled steel sheet - Google Patents

Abstract

A method of manufacturing a hot-rolled steel sheet is provided to minimize a yield reduction due to cutting off a width end for removing seam defects on a steel sheet.
SOLUTION: A shape meter 3 installed on the downstream side of a width rolling device 2 installed in a hot rolling line measures the shape of one width end portion of the rolled material subjected to width rolling, and the measured width end. Based on the shape of the part, the occurrence region of wrinkles generated in the rolling process after the width rolling device 2 of the material to be rolled 1 is predicted, the width cut-off amount is estimated, and the width cut-off is performed based on the estimated width cut-off amount. A method for producing a hot-rolled steel sheet, comprising: Furthermore, the height setting of the die of the width rolling device 2 for the rolled material following the material to be rolled is determined.
[Selection] Figure 1

Description

  The present invention relates to a method for producing a hot-rolled steel sheet that minimizes yield reduction due to width end truncation for removing seam defects of a material to be rolled in hot rolling.

  Conventionally, various forms of detection of the end face of a material to be rolled have been performed in the middle of a process called rough rolling in hot rolling. For example, a width meter that can continuously measure the width of a hot slab slab (which can measure the shape profile of the steel plate end face) is commercially available. The sensor of this width meter measures the end face shape immediately after the rolled material passes through the horizontal rolling mill, and estimates the amount of width expansion or contraction of the material to be rolled in the subsequent rolling process based on the measurement result. It is intended to be used for.

  Moreover, regarding the width fluctuation of the steel sheet by horizontal rolling and width rolling in rough rolling, for example, there is a description in Non-Patent Document 1, and it is very useful in width control to actually measure the steel sheet width in the middle of rolling. I know that there is.

  In hot rolling, rectangular steel ingots called slabs are processed into steel plates by repeating horizontal rolling. In this horizontal rolling process, the front and back ends of the steel plates rotate around the end faces when they were slabs. Formed. At that time, wrinkles called seam wrinkles occur on the front and back surfaces. The mechanism of the generation of wrinkles is described in paragraph number [0007] of Patent Document 1, for example.

  4 (b), (c), FIG. 10, and FIGS. 15 (a), (b) in Patent Document 1, the width rolling tool is always vertically symmetrical in the thickness direction of the slab during each width rolling. However, it is not easy to make it vertically symmetrical in actual rolling.

This is because, as described in Non-Patent Document 1 mentioned above, when width rolling is performed, the slab is thickened as a three-dimensional deformation in the plate thickness direction, but the slab is constrained with its lower surface in contact with the transport roll. . In order to cope with this, Patent Document 2 discloses a technique for adjusting the height of the exit side table of the die for width reduction (press) in advance of the amount of increase in thickness.
JP 2002-137001 A Japanese Patent Publication No. 3-38921 "Theory and practice of sheet rolling", edited by Japan Iron and Steel Institute, 1984, p72-p77

  However, in the technique disclosed in Patent Document 2, although the relationship between the width reduction amount and the thickness increment (thickening amount) is shown in FIG. 2, this relationship is the temperature during rolling, the slab width before rolling, There is a problem that an error always occurs in the prospect of the increase in thickness because it varies greatly depending on the slab thickness.

  And, due to the expected error of this thickening amount, the width reduction mold does not hit the center in the slab height direction, and the width edge of the seam trough generated on the upper and lower surfaces of the steel plate by the subsequent horizontal rolling process The distance from the part is inconsistent.

  Also, when the slab to be transported is twisted or the mounting height of the width reduction die to the width reduction device is shifted left and right, the position of the mold transferred by the press becomes asymmetrical in the vertical direction, and the upper surface of the steel plate And the distance from the width end portion of the seam ridge generated on the lower surface is inconsistent.

  And this seam trough is cut off along with the width end in the cold rolling process etc. following hot rolling. At this time, if a vertically asymmetric seam trough is generated, it is regarded as vertically symmetrical and the width end is cut off. In such a case, seam wrinkles remain, which reduces the product yield. Also, the amount of truncation increases when trying to completely remove seams. That is, the vertical rolling under the width reduction minimizes the yield reduction due to the seam wrinkles.

  In view of these problems of the prior art, an object of the present invention is to provide a method for producing a hot-rolled steel sheet for minimizing the yield reduction due to the width edge truncation for removing seam wrinkles on the steel sheet.

  The invention according to claim 1 of the present invention measures the shape of the width end portion of the width-rolled material by a shape meter installed on the downstream side of the width rolling apparatus installed in the hot rolling line, Based on the measured shape of the width end portion, predict the occurrence region of wrinkles generated in the rolling process after the width rolling device of the material to be rolled, estimate the width cut-off amount, and based on the estimated width cut-off amount The method of manufacturing a hot-rolled steel sheet is characterized by performing width cutting.

  The invention according to claim 2 of the present invention is the method of manufacturing a hot-rolled steel sheet according to claim 1, wherein when the width is cut off based on the estimated width cut-off amount, the material to be rolled is scheduled in the final step. When the product width required for the product which has been subjected to the above process cannot be taken, it is diverted as a material for another product.

  Furthermore, the invention according to claim 3 of the present invention is to measure the shape of the width end of the material to be rolled by the shape meter installed on the downstream side of the width rolling device installed in the hot rolling line, A hot-rolled steel sheet manufacturing method comprising: determining a height setting of a die of a width rolling device for another rolled material following the material to be rolled based on the shape of the measured width end portion. .

  The present invention is a shape meter that measures the width end face shape installed immediately after the width rolling mill, and measures the vertical asymmetry in the thickness direction at the time of width rolling, thereby generating seam wrinkles generated on the upper and lower surfaces of the steel sheet. It was possible to predict in advance the disagreement of the distance from the edge of the width, and the width cut-off amount could be estimated.

  In addition, if the width cut-off amount is excessive and the product width required for the product to be rolled in the final process cannot be taken, the product in the final process can be transferred to another product. Defects could be prevented. Furthermore, if the obtained end face shape is asymmetrical in the vertical direction, review the setting of the height of the press die of the other rolled material that follows, so that the width rolling is symmetrical in the thickness direction, and the width It was also possible to minimize products that were overcut.

  FIG. 1 is a diagram showing an apparatus configuration example for carrying out the present invention. In the figure, 1 is a material to be rolled, 2 is a width rolling device (sizing press), 3 is a shape meter, and 4 is a rough horizontal mill.

  There is a sizing press as a width rolling device 2 that width-rolls the material 1 (hereinafter also referred to as a slab) after exiting a heating furnace (not shown) in the hot rolling process. A shape meter 3 for measuring the shape of the end face of the material to be rolled 1 is installed immediately after the width rolling device 2. The shape meter 3 may be of any method as long as it can measure the shape of the end face. For example, the shape meter 3 includes a laser transmitter and a CCD camera, and measures a two-dimensional slab end face by a light cutting method. Since the slab is conveyed in the conveyance direction in the figure, the three-dimensional shape of the end face can be obtained by developing the two-dimensional information in the slab longitudinal direction.

  FIG. 2 is a diagram showing a cross-sectional shape of a die pressing surface of a sizing press. And FIG. 3 is a longitudinal cross-sectional view which shows the side surface shape of the to-be-rolled material width-symmetrically rolled up and down as a result of the rolling by the metal mold | die shown in FIG.

  The shape of the mold is transferred to the end face shape measured by the shape meter 3, and it can be seen from this transferred shape whether the mold is in contact with the slab in a vertically symmetrical manner. That is, if the shape of the mold transferred to the slab is vertically symmetric, it is considered that the mold is in contact with the center of the slab. Minimal.

  FIG. 4 is a longitudinal sectional view showing a side shape of a material to be rolled that has been asymmetrically width-rolled. As described above, when the obtained end face shape is asymmetrical in the vertical direction, the necessary width cut-off amount is estimated from the deviation amount. Thereby, even when the end face shape is asymmetrical in the vertical direction, it is possible to accurately estimate the width cut-off amount that does not leave the seam wrinkles.

  At this time, if the width cut-off amount becomes excessive, the product width required for the product that the material to be rolled was scheduled in the final process may not be taken. In this case, a product defect in the final process is prevented by diverting it as a material for another product.

  In addition, when the end face shape measured by the shape meter 3 is asymmetric in the vertical direction, the height setting of the press die of the material to be rolled following the measured material to be rolled is reviewed, and the width symmetrical in the thickness direction is reviewed. Try to roll and minimize products that have excessive width cuts.

  FIG. 5 is a diagram illustrating a position where a seam wrinkle generating portion after horizontal rolling is cut off. In FIGS. 5 (a) and (b), the case of vertical symmetry and the case of vertical asymmetry are shown, respectively, and how typical locations (1-6) after width reduction will become after horizontal rolling This is schematically shown. It can be seen that the position where the seam wrinkle generation portion is cut off differs between the case of vertical symmetry and the case of asymmetry of vertical, and the amount of cut off increases in the case of vertical asymmetry.

  As explained above, it is a shape meter that measures the width end face shape installed immediately after the width rolling mill, and it is generated on the upper and lower surfaces of the steel sheet by measuring the vertical asymmetry in the thickness direction during width rolling. It is possible to predict in advance the disagreement of the distance from the width edge of the seam ridge, and the width cut-off amount can be estimated.

  Moreover, when the amount of width cut-off is excessive and the product width required in the final process cannot be taken, the product defect in the final process can be prevented by diverting it as a material for another product. Furthermore, if the obtained end face shape is asymmetrical in the vertical direction, review the setting of the height of the press die of the other rolled material that follows, so that the width rolling is symmetrical in the thickness direction, and the width It is also possible to minimize products that are excessively cut off.

  An embodiment targeting the slab with the apparatus configuration shown in FIG. 1 will be described below. When the end face shape measured by the shape meter 3 is asymmetrical in the vertical direction, the slab to be transported may be twisted (FIG. 6) in addition to the case where the increase in thickness is expected. It was confirmed even when the mounting height to the width reduction device was shifted left and right (FIG. 7).

  As a result of the width rolling of the slab, the end face of the slab was estimated to be 20 mm on one side when the end face shape was asymmetrical as shown in FIG. In the case of vertical symmetry as shown in FIG. 3 described above, the width cut-off amount is 15 mm on one side, and the original product width has become narrower by 10 mm on both ends.

  The product size of the coil manufactured from this slab was 3.5 mm × 1200 mm, but the maximum product size was 1190 mm due to the increase of the width cut-off amount. Therefore, it was changed to manufacture another product of 4.0 mm × 1190 mm.

  Further, since the end face shape of the slab is 3 mm as shown in FIG. 4 as compared to the case of vertical symmetry, it can be seen that the press mold is in contact with the slab thickness 3 mm higher than the center of the slab. By setting the height of the press die of the rolled material to −3 mm, the end face shape of the subsequent rolled material becomes vertically symmetric as shown in FIG. 3, and the width cut-off amount can be kept to a minimum of 15 mm. .

It is a figure which shows the example of an apparatus structure for implementing this invention. It is a figure which shows the cross-sectional shape of the metal mold | die press surface of a sizing press. It is a longitudinal cross-sectional view which shows the side surface shape of the to-be-rolled material width-rolled symmetrically up and down. It is a longitudinal cross-sectional view which shows the side shape of the to-be-rolled material width-rolled asymmetrically up and down. It is a figure which shows the position which discards the seam wrinkle generation | occurrence | production part after horizontal rolling. It is a longitudinal cross-sectional view which shows the side surface shape of the to-be-rolled material by which the to-be-rolled material was conveyed right and left twisted, and was width-rolled asymmetrically up and down. It is a longitudinal cross-sectional view which shows the side shape of the to-be-rolled material rolled width-symmetrically up and down because the height of the metal mold | die of right and left shifted | deviated.

Explanation of symbols

1 Rolled material 2 Width rolling equipment (sizing press)
3 Shape meter 4 Coarse horizontal mill

Claims (3)

By the shape meter installed on the downstream side of the width rolling device installed in the hot rolling line, the shape of the width end of the material to be rolled is measured,
Based on the measured shape of the width end portion, the generation region of wrinkles generated in the rolling process after the width rolling apparatus of the material to be rolled is predicted, the width cut-off amount is estimated, and the estimated width cut-off amount is set. A method of manufacturing a hot-rolled steel sheet, wherein the width is cut off based on the method. In the manufacturing method of the hot-rolled steel sheet according to claim 1,
When the width cut is performed based on the estimated width cut-off amount, if the product width required for the product that the material to be rolled is scheduled in the final process cannot be taken, it should be diverted as a material for another product. A method for producing a hot-rolled steel sheet. By the shape meter installed on the downstream side of the width rolling device installed in the hot rolling line, the shape of the width end of the material to be rolled is measured,
A method for producing a hot-rolled steel sheet, comprising: determining a height setting of a die of a width rolling apparatus for another rolled material following the material to be rolled based on the measured shape of the width end portion.