JP6308178B2 - Hot slab width pressing method - Google Patents

Description

  The present invention relates to a hot slab width pressing method in which a hot slab is width-pressed by a width press device provided with a buckling prevention roll.

  A pair of presses installed in the plate width direction as a device for making slabs of the same width manufactured in a continuous casting process into different widths according to product specifications in the hot-rolled steel plate manufacturing process. A width press device that intermittently rolls down the hot slab in the plate width direction with a mold and a vertical roll with an axis in the vertical direction are arranged one by one on the left and right sides of the slab width direction. A width reduction device is generally used. As a conventional technique regarding the width reduction of the slab, there is a technique disclosed in Patent Document 1, for example. In this method, the width is first roughly changed by a width press (sizing press) and then smoothed by vertical roll rolling to obtain a desired width.

  In the width reduction by this width press apparatus, the width reduction of about 300 to 350 mm is usually performed on the hot slab having a width of about 900 to 2000 mm. From the slab cast to the same width by continuous casting. This makes it possible to manufacture steel sheet products with different widths according to manufacturing specifications.

  However, since the shape of the hot slab used for thin plate manufacturing has a large width-to-thickness ratio of about 3 to 10, the width reduction (width pressing amount) is about 250 mm or more. As shown in an example in FIG. 5, a buckling phenomenon is likely to occur in the hot slab 20 in the upward or downward direction. In addition, 20a is a front-end | tip part of a hot slab, 20b is a stationary part of a hot slab, and 20c is a tail end part of a hot slab.

  As a technique for preventing such a slab buckling phenomenon, as shown in FIG. 6, when the hot slab 20 is intermittently reduced in width by the mold 22 in the width press apparatus, There is a technique of appropriately using a buckling prevention roll 21 sandwiched in the vertical direction (for example, Patent Document 2).

  According to the present method, the amount of slab thickening due to width reduction is predicted as a function of the width of the slab before width reduction, the amount of width reduction, the thickness of the slab before width reduction, at each of the tip and the steady portion, The height position of the roll is set so that the upper and lower buckling prevention rolls are in contact with the center portion of the slab width after the thickness increase.

  On the other hand, as one of the wrinkles that are particularly likely to occur when hot rolling stainless steel, there is a wrinkle called an edge seam. This edge seam is generated as the rolling progresses, and the corner side surface of the material to be rolled is compressed and wrinkles, and further, as the rolling proceeds, the wrinkles wrap around the surface of the material to be rolled. .

  In order to suppress the occurrence of edge seam wrinkles, for example, Patent Document 3 discloses a technique for making the side surface of the mold 22 of the width press apparatus convex as shown in FIG. Further, Patent Document 4 discloses an abnormality detection technique for detecting in advance that an edge seam is enlarged due to an abnormality in a mold position control mechanism of a width press device when such a convex mold is used. Is disclosed.

  Patent Document 5 discloses a width characterized by measuring a slab side surface shape after width pressing, and performing a width press by aligning the center of the slab side surface with the mold center of the width pressing device. A pressing method is disclosed.

JP 60-141301 A JP 2011-140056 A Japanese Patent No. 2586769 Japanese Patent No. 4457888 Japanese Patent No. 5582288

  However, although the method described in Patent Document 2 is effective in preventing the buckling phenomenon of the material to be rolled, the position of the buckling prevention roll is set by a function calculated in advance. It is not possible to cope with changes in the press position in the height direction due to fluctuations in the pass line height due to wear of the die position control mechanism and buckling prevention roll. Therefore, when the said invention is applied to stainless steel, there exists a problem that the expansion of an edge seam cannot be prevented.

  On the other hand, in the method described in Patent Document 4, the occurrence of edge seam can be prevented, but as a subsequent treatment, adjustment of the mold position control mechanism of the width press device and the height position of the buckling prevention roll Since the adjustment is performed mainly by measuring the machine position, there is a problem that the line is stopped and the productivity is hindered.

  Further, in the method described in Patent Document 5, the shape of the side surface of the slab after the width press is measured, but in this method, whether the error of the press hitting position is caused by the misalignment of the press die, or It is difficult to clearly distinguish whether it is caused by the positional deviation of the roll for the buckling prevention roll described above. Therefore, if this error is caused by an error in the function that predicts the increase in slab thickness due to width reduction, the correction of the position calculated by measuring a material with a large width reduction amount will result in a material with a small width reduction amount. On the other hand, it will be overcompensated.

  Therefore, the object of the present invention is to prevent the bending due to buckling of the material to be rolled even when the width reduction amount is large, and to perform a stable operation, and to prevent the stainless steel without impairing the productivity. An object of the present invention is to provide a hot slab width press method capable of preventing the occurrence of edge seam defects during hot rolling.

In order to solve the above-mentioned problems, the present invention provides a method for reducing the buckling of a hot slab intermittently by means of a width press device provided with buckling prevention rolls on an upper side and a lower side of a slab pass line. A width pressing method for a hot slab, wherein the height position of the prevention roll is adjusted according to a predicted value of the thickness increase of the thickness and thickness of the tip portion and the steady portion of the hot slab due to width reduction, the width pressing device With respect to the hot slab after pressing on the exit side, the height He from the pass line of the end surface of the hot slab and the hot slab are measured by a two-dimensional non-contact distance meter installed above the exit side of the width press device. The height Hc from the center pass line is measured, the thickness increase amount ΔH _cj in the center in the width direction is calculated based on the He and the Hc, and the value of the ΔH _cj and the hot slab calculated in advance compared with the predicted value ΔH _cy of the thickening amount And allows to calculate the error [Delta] H _CYU the thickening amount of meat quantity per increase of unit as a correction term, the height position of the buckling preventing roll when the width press next hot slabs based on this The present invention provides a hot slab width pressing method characterized by adjusting.

  According to the present invention, the height position of the buckling prevention roll can be accurately set at the center in the thickness direction of the hot slab. For this reason, even when the amount of width reduction is large, it is possible to prevent bending due to buckling of the material to be rolled and perform stable operation, and when stainless steel is hot-rolled without impairing productivity. The occurrence of edge seam defects can be prevented.

It is a block diagram which shows the hot rolling line used in order to implement the width press method of the hot slab which concerns on one embodiment of this invention. It is a figure which shows the arrangement position of the two-dimensional non-contact distance meter provided in the hot rolling line of FIG. 1, (a) is a top view, (b) is sectional drawing by BB line. It is the figure which showed the measurement amount in a two-dimensional non-contact distance meter. It is a figure which shows the result of the Example of this invention. It is a perspective view which shows the state of the slab buckled by the width reduction. It is a perspective view which shows the width press apparatus which provided the buckling prevention roll. It is a figure which shows the mode of the width reduction of the hot slab by a convex metal mold | die.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
FIG. 1 is a block diagram showing a hot rolling line used for carrying out a hot slab width pressing method according to an embodiment of the present invention.

  As shown in FIG. 1, the hot rolling line has a continuous heating furnace 1, a width press device 2, a roughing mill 3, a finishing mill 4, and a winder 5. These are controlled by the control device 6. The control device 6 performs a control operation based on a command from the host computer 7. A two-dimensional non-contact distance meter 8 is provided on the exit side of the width press device 2.

  The width press device 2 includes a die for reducing the width of a hot slab, which is a material to be rolled, and rolls for preventing buckling provided on the upper side and the lower side of the slab pass line. Inter-slab slabs are intermittently reduced in width. The rough rolling mill 3 includes a vertical roll rolling mill 11 and a horizontal roll rolling mill 12.

  As shown in FIGS. 2 (a) and 2 (b), the two-dimensional non-contact distance meter 8 is provided on one side or both sides on the exit side (downstream side) of the table roller 13 of the width press device 2 in the hot rolling line. Are provided so as to monitor the oblique upper side surface of the hot slab 10. That is, the two-dimensional non-contact distance meter 8 is installed at an obliquely upper position of the hot slab 10 (shown in FIG. 2 is installed on both sides of the table roller 13). With this two-dimensional non-contact distance meter 8, as shown in FIG. 3, the height He from the pass line of the end surface of the hot slab 10 and the height Hc from the pass line at the center in the width direction of the hot slab 10 are obtained. Is measured. The measurement value of the two-dimensional non-contact distance meter 8 is transmitted to the control device 6 via the host computer 7. Here, the installation position of the two-dimensional non-contact distance meter 8 is set obliquely above the hot slab 10 because the vertical direction of the material to be rolled is extremely large as the environment for installing the distance meter due to radiant heat and steam from the material to be rolled. This is because it is poor.

  In the hot rolling line configured as described above, after the hot slab 10 is heated in the continuous heating furnace 1, the width press apparatus 2 buckles the upper side and the lower side of the slab pass line. While preventing the buckling of the hot slab 10 by the prevention roll, the width is intermittently reduced by the mold. After that, the width is further reduced by the vertical roll of the vertical roll mill 11 in the rough rolling mill 3, and after the finish rolling mill 4, the roll is wound by the winder.

  At this time, when the two-dimensional non-contact distance meter 8 is installed on one side of the table roller 13, the oblique upper side surface of the hot slab 10 is monitored on the outlet side (downstream side) of the width press device 2 in the hot rolling line. The height He from the pass line of the end surface of the hot slab 10 shown in FIG. 3 and the height Hc from the pass line at the center in the width direction of the hot slab 10 are measured.

This measured value is transmitted to the control device 6 via the host computer 7. Then, the following calculation is performed in the control device 6.
The thickness increase amount ΔH _{cj at the} center in the width direction is calculated by, for example, the following expression (1), where tc is the slab thickness before width reduction.
ΔH _cj = Hc− (He−Hc) −tc (1)

When the two-dimensional non-contact distance meter 8 is installed on both sides of the table roller 13, the height from the pass line of the end surface of the hot slab 10 at that time is He _op and He _dr on the working side and the driving side, respectively. Then, the thickness increase amount ΔH _{cj at the} center in the width direction is calculated by, for example, the following equation (2).
ΔH _cj = Hc − {(He _op −Hc) + (He _dr −Hc)} / 2−tc (2)

  On the other hand, in order to adjust the height position of the buckling prevention roll of the width press device 2, the control device 6 uses the method described in Patent Document 2 and the like in advance so that the front end portion of the hot slab 10 due to width reduction and the steady state. The plate thickness increase amount of the part is calculated.

Then, the control device 6 compares ΔH _cj calculated as described above with the predicted value ΔH _cy of the increase in _{thickness of the} hot slab 10 calculated in advance, and increases the increase per unit increase in _thickness. The meat amount error ΔH _cyu is calculated by the following equation (3).
ΔH _cyu = (ΔH _{cj −ΔH cy} ) / ΔH _cy (3)

Using the thus calculated error ΔH _cyu of the increase in _thickness as a correction term per unit increase in _thickness , the _predicted increase in _thickness at the next rolling is corrected to ΔH _cn and set.

  At this time, in order to prevent a sudden change in the position of the buckling prevention roll, the correction value may be set by smoothing by a method such as exponential smoothing or moving average.

Then, in the next rolling, to adjust the height position of the width pressing device 2 buckling preventing roll on the basis of the corrected thickening amount prediction value [Delta] H _cn. As a result, the height position of the buckling prevention roll can be accurately adjusted to the thickness of the hot slab even if the height of the pass line changes due to wear of the die position control mechanism of the width press device or the buckling prevention roll. It can be set in the center of the direction. For this reason, even when the amount of width reduction is large, it is possible to prevent bending due to buckling of the material to be rolled and perform stable operation, and when stainless steel is hot-rolled without impairing productivity. The generation of edge seams can be suppressed.

Examples of the present invention are shown below.
The present invention was implemented with the equipment layout as shown in FIG. The thickness increase ΔH _{cy in the} center in the width direction of the hot slab, which is the material to be rolled, predicted by the conventional method, and the increase in the center in the width direction of the rolled material calculated from the measured value by the two-dimensional non-contact distance meter. From the amount of wall thickness ΔH _cj and the amount of increase in wall _thickness ΔH _{cny at the} center in the width direction of the next rolled material predicted by the conventional method, the amount of increase in wall _thickness ΔH _cn at the center in the width direction at the next rolling is _expressed by the following equation (4): Calculated and set by
ΔH _cn = ΔH _cny * (1 + k * ΔH _cyu )
= ΔH _cny * {1 + k * (ΔH _cj −ΔH _cy ) / ΔH _cy } (4)
Here, k was set to 0.5.

4, the thickness increase amount calculation results in the width direction central portion of the present invention [Delta] H _cn, and meat quantity calculation results [Delta] H _(cny) of the respective increase of the widthwise central portion by the conventional method, the actual thickening amount in the width direction central portion The difference is shown.

  As shown in FIG. 4, the standard deviation of the prediction result was reduced from 18.2 mm of the conventional method to 3.6 mm of the present invention, and the usefulness of the present invention was shown.

DESCRIPTION OF SYMBOLS 1 Continuous heating furnace 2 Width press apparatus 3 Rough rolling mill 4 Finish rolling mill 5 Winding machine 6 Control apparatus 7 Host computer 8 Two-dimensional non-contact distance meter 10 Hot slab 11 Vertical roll rolling mill 12 Horizontal roll rolling mill 13 Table Roller 20 Hot slab 20a Hot slab tip 20b Hot slab steady part 20c Hot slab tail end 21 Buckling prevention roll 22 Mold

Claims (1)

When the hot slab is intermittently subjected to width reduction by a width press device provided with buckling prevention rolls on the upper side and lower side of the slab pass line, the height position of the buckling prevention roll is determined by width reduction. A hot slab width press method that adjusts according to the predicted value of the thickness increase of the thickness of the tip and the steady part of the hot slab,
With respect to the hot slab after pressing on the exit side of the width press device, the height He from the pass line of the end surface of the hot slab is measured by a two-dimensional non-contact distance meter installed above the exit side of the width press device. and the height Hc from the hot slab central pass line was measured, the calculating the thickness increase amount [Delta] H _cj of the widthwise central portion on the basis of He and the Hc, there are previously calculated value of the [Delta] H _cj By comparing with the predicted value ΔH _cy of the increased _thickness of the hot slab, the error ΔH _cyu of the increased _thickness per unit increased _thickness is calculated as a correction term, and based on this, the error of the next hot slab is calculated. A width pressing method for a hot slab, wherein the height position of the buckling prevention roll is adjusted during width pressing.

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