JP2906988B2 - Method of controlling width of steel sheet in hot rolling - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling the width of a steel sheet in hot rolling, and more particularly to a hot rolling method capable of greatly reducing the deviation between a product sheet width and a target sheet width of a steel sheet. And a method for controlling the width of a steel sheet in the above.

[0002]

2. Description of the Related Art A hot-rolled steel sheet is manufactured according to a side view showing a manufacturing line shown in FIG. In FIG. 6, 1 is a heating furnace for heating the slab to a predetermined temperature, 2 is a rough rolling mill composed of a plurality of horizontal roll rolling mills 3 and vertical roll rolling mills 4, and 5 is a rough rolling mill. Subsequently, a finishing rolling mill comprising a plurality of horizontal roll rolling mills, 6 is a cooling zone for cooling the steel plate 7 on the hot run table to a predetermined temperature, and 8 is a winding band for winding the steel plate 7 It is a coiler.

[0003] A slab heated to a predetermined temperature by the heating furnace 1 is roughly rolled by a rough rolling mill 2 and then rolled into a steel sheet 7 having a predetermined thickness by a finish rolling mill 5. Next, the steel sheet 7 was cooled while moving on the hot run table.
Is cooled to a predetermined temperature, and then wound around the coiler 8.

Conventionally, as described above, the width control of a steel sheet in hot rolling is performed by a width roll provided by a vertical roll rolling machine 4 of a rough rolling mill 2 and a looper 9 provided between a horizontal roll rolling mill of a finish rolling mill 5 (see FIG. 1). According to FIG. 7), the tension is adjusted on the steel sheet 7 between the horizontal roll mills.

[0005]

However, the above-mentioned prior art has the following problems. That is, in the conventional hot rolling, the width control of the steel sheet is performed in the rolling stage in the rough rolling mill 2 or the finishing mill 5, that is, the width control is performed in the semi-finished product stage of the steel sheet. It is difficult to make the final product sheet width close to the target sheet width due to a problem such as a decrease in the sheet width due to an increase in the temperature of the steel sheet due to accelerated cooling of the steel sheet. Further, in the sheet width control method using the looper 9, since the material flow between the horizontal roll mills, that is, the mass flow also fluctuates, the influence of disturbance is large and sufficient width control cannot be performed.

Accordingly, an object of the present invention is to control the sheet width after finish rolling, thereby greatly reducing the deviation between the product sheet width and the target sheet width. An object of the present invention is to provide a method for controlling a sheet width.

[0007]

According to the present invention, a heated slab is hot-rolled by a finishing mill into a steel sheet having a predetermined thickness, and then the steel sheet thus hot-rolled to a predetermined thickness is formed. Cooling to a predetermined temperature by a cooling zone following the finishing mill, and winding the steel sheet thus cooled to a predetermined temperature into a coiler, when manufacturing a steel sheet having a predetermined thickness and characteristics, Finish rolling of the steel sheet at a temperature equal to or higher than the Ar ₃ transformation point, previously determined for each product size and steel type, measuring the sheet width of the steel sheet immediately after the Ar ₃ transformation point position of the steel sheet on the hot run table, Calculate the deviation between this plate width measurement value and the target plate width,
Then, based on the relationship between the tension applied to the steel sheet and the amount of shrinkage of the sheet width, which has been determined in advance for each product size and steel type, a tension that makes the deviation zero is set between the coiler and the finishing mill. It is characterized in that it is applied to the steel plate in between.

[0008] The tension applied to the steel sheet between the coiler and the finishing mill can be adjusted by controlling the rotation speed of the coiler.

[0009]

It is known that when a steel sheet is cooled in a state where tension is applied in the longitudinal direction, the steel sheet shrinks in width at a temperature near the Ar ₃ transformation point. And this width | variety shrinkage has a fixed relationship with the tension | tensile_strength given to a steel plate.
Thus ends the finish rolling of the steel sheet than the Ar ₃ transformation point temperature, and measuring the strip width at the Ar ₃ transformation point positions, it calculates the deviation between the measured value and the target plate width, this deviation If a tension such that it becomes zero is applied to the steel sheet between the coiler and the finish rolling mill, the width of the steel sheet can be controlled after the finish rolling. And the deviation between the product plate width and the target plate width can be greatly reduced without being affected by disturbances in the case of tension control by a looper.

[0010] If the current supplied to the mandrel of the coiler is adjusted to control the number of rotations of the mandrel, the tension applied to the steel sheet between the coiler and the finishing mill can be easily adjusted.

[0011]

Next, an embodiment of a method for controlling the width of a steel sheet in hot rolling according to the present invention will be described with reference to the drawings.

FIG. 1 is a side view showing one embodiment of the method for controlling the width of a steel sheet in hot rolling according to the present invention.

In FIG. 1, reference numeral 10 denotes a finishing mill comprising a plurality of horizontal roll mills, 11 denotes a cooling zone for cooling the steel plate 7 on a hot run table to a predetermined temperature, and 12 denotes a steel plate. Coiler for winding up, 13
Is a width meter for measuring the width of the steel plate 7 in the Ar ₃ transformation region, and 14 is the coiler 1 as described later.
2 is a controller for controlling the number of rotations of the mandrel and adjusting the tension applied to the steel plate 7 between the coiler 12 and the finishing mill 10.

A slab heated to a predetermined temperature by a heating furnace (not shown) is roughly rolled by a rough rolling mill (not shown), and then rolled to a steel sheet 7 having a predetermined thickness by a finishing mill 10. . Next, the steel sheet 7 is cooled to a predetermined temperature by the cooling zone 11 while moving on the hot run table, and is wound around the coiler 12.

In the present invention, between the time when the front end of the steel sheet 7 is wound by the coiler 12 and the time when the rear end of the steel sheet 7 exits the finishing mill 10, the steel sheet between the coiler 12 and the finishing mill 10 is removed. 7 is tensioned. This tension is adjusted by the controller 14 controlling the rotation speed of the mandrel of the coiler 12 as described later.

When the finish rolling of the steel sheet 7 is completed at a temperature equal to or higher than the Ar ₃ transformation point, as shown in FIG. 2, the steel sheet 7 turns to the Ar ₃ transformation temperature on the hot run table. This causes width reduction. As shown in FIG. 3, the tension applied to the steel sheet 7 and the width shrinkage amount of the steel sheet 7 at this time have a relationship in which the greater the tension (stress) applied to the steel sheet 7, the larger the width shrinkage amount of the steel sheet 7 becomes. .

The controller 14 calculates the deviation between the width of the steel plate 7 at the Ar ₃ transformation position measured by the width gauge 13 and the target width, and uses the relationship shown in FIG. Find the tension such that the deviation between the target plate width and the target plate width becomes zero,
Then, the current supplied to the mandrel of the coiler 12 is adjusted so that the tension obtained in this manner is applied to the steel plate 7 between the coiler 12 and the finishing mill 10, and the rotation speed of the mandrel is controlled. . As a result, the deviation between the product plate width and the target plate width can be reduced to a level of 1 mm or less, and the later-described plate width variation of the steel plate 7 can be reduced to ± 1 mm or less.

Next, an embodiment of the method for controlling the width of a steel sheet in hot rolling according to the present invention will be described.

According to the method of the present invention, the product thickness 1.6.
mm, a product sheet width of 900 mm, and 10 hot rolled steel sheets having a carbon equivalent of 0.01%. At this time, the temperature of the steel sheet on the exit side of the finish rolling is 850 ° C, and the temperature of the steel sheet before winding is 640 ° C.
Met. The sheet width deviation (x ₁ ) and the sheet width variation (x ₂ ) of the product coil thus manufactured were measured. The results are shown in Table 1 together with the results of the above-described conventional technology. The sheet width deviation (x ₁ ) is the length between the valley of the sheet width fluctuation curve and the target sheet width, as shown in FIGS.
The board width variation (x ₂ ) is the length between the peak and the valley of the board width variation curve. FIG. 4 shows the sheet width deviation on the exit side of the finishing mill. FIG. 5 is a graph showing the sheet width deviation after controlling the sheet width by the method of the present invention.

[0020]

As is clear from Table 1, according to the present invention, the sheet width deviation (x ₁ ) and the sheet width variation (x ₂ ) are significantly smaller than those of the prior art method. It has been found that the deviation between the width and the target plate width can be significantly reduced.

[0022]

Effect of the Invention] As described above, according to the present invention, to terminate the finish rolling of the steel sheet than the Ar ₃ transformation point temperature, and measuring the strip width at the Ar ₃ transformation point position, the measured value By calculating the deviation between the target plate thickness and the tension such that this deviation becomes zero, by applying to the steel plate between the coiler and the finish rolling mill, the width control of the steel plate after finish rolling. Therefore, an industrially useful effect such that the thickness deviation from the target thickness can be significantly reduced is provided.

[Brief description of the drawings]

FIG. 1 is a side view showing one embodiment of a method for controlling the width of a steel sheet in hot rolling according to the present invention.

FIG. 2 is a graph showing a temperature change of a steel sheet from a finishing mill to a coiler.

FIG. 3 is a graph showing the relationship between the tension applied to a steel sheet and the amount of width reduction of the steel sheet.

FIG. 4 is a graph showing sheet width fluctuation on the exit side of a finishing mill.

FIG. 5 is a graph showing sheet width fluctuation after sheet width control according to the present invention.

FIG. 6 is a side view showing a conventional steel sheet manufacturing line.

FIG. 7 is an explanatory diagram of a looper.

[Explanation of symbols]

 1: heating furnace, 2: rough rolling mill, 3: horizontal rolling mill, 4: vertical rolling mill, 5: finishing rolling mill, 6: cooling zone, 7: steel plate, 8: coiler, 9: looper, 10: Finishing mill, 11: cooling zone, 12: coiler, 13: width gauge, 14: controller.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) B21B 37/16

Claims (2)

(57) [Claims] 1. A heated slab is hot-rolled by a finishing mill into a steel sheet having a predetermined thickness, and the steel sheet thus hot-rolled to a predetermined thickness is cooled by a finishing mill. Cooled to a predetermined temperature by a band, and by winding the steel sheet thus cooled to a predetermined temperature into a coiler, when manufacturing a steel sheet having a predetermined sheet width and characteristics, at a temperature not lower than the Ar ₃ transformation point. terminate the finish rolling of the steel sheet, obtained in advance for each product size and steel grade, the steel sheet of the plate width was measured in the steel sheet immediately after Ar ₃ transformation point of the steel plate on the hot run table, were determined in this way The deviation between the measured sheet width and the target sheet width was calculated, and determined in advance for each product size and steel type.
On the basis of the relationship between the tension applied to the steel sheet and the amount of shrinkage of the sheet width, a tension that makes the deviation zero is applied to the steel sheet between the coiler and the finishing mill. , A method of controlling the width of a steel sheet in hot rolling. 2. A tension is applied to the steel sheet by controlling a rotation speed of the coiler.
The method for controlling the width of a steel sheet in hot rolling according to claim 1.