JP6756312B2 - Manufacturing method of thick steel plate - Google Patents

Description

The present invention relates to a method for manufacturing a thick steel sheet.

When a thick steel sheet is manufactured by controlled rolling, etc., when the rolled material reaches a predetermined plate thickness (for example, controlled rolling start plate thickness), until it reaches a predetermined target temperature (for example, controlled rolling start temperature). As a device to shorten the waiting cooling time, a passing cooling type cooling equipment (water cooling equipment) is installed near the reversible rolling mill, and the pass schedule is cooled by the passing cooling type cooling equipment while rolling with the reversible rolling mill. A method of incorporating a rolling / cooling pass is performed (for example, Patent Documents 1 to 3).

Japanese Unexamined Patent Publication No. 2015-911604 Japanese Unexamined Patent Publication No. 2011-147962 Japanese Unexamined Patent Publication No. 2011-143462

However, in the above-mentioned Patent Documents 1 to 3, rolling in which a predetermined target temperature (for example, controlled rolling start temperature) is obtained when the rolled material reaches a predetermined plate thickness (for example, controlled rolling start plate thickness).・ The focus is on determining the cooling pattern (number of rolling / cooling passes, whether or not rolling is performed on a reversible rolling mill in each rolling / cooling pass), and rolling efficiency is not considered very much. There was a problem.

The present invention has been made in view of the above circumstances, and when manufacturing a thick steel sheet, a passing cooling type cooling facility is installed in the vicinity of the reversible rolling mill, and the reversible rolling mill is set in the path schedule. In the case of incorporating a rolling / cooling path that cools with a passing cooling type cooling facility while rolling in (for example, when a thick steel sheet is manufactured by controlled rolling), it is possible to both secure the target temperature and improve the rolling efficiency. It is an object of the present invention to provide a method for manufacturing a thick steel sheet.

In order to solve the above problems, the present invention has the following features.

[1] When manufacturing thick steel sheets, a pass-cooling type cooling facility is placed close to the reversible rolling mill, and rolling / cooling is performed by the pass-cooling type cooling facility while rolling with the reversible rolling mill according to the pass schedule. When incorporating the pass, the upper limit of the number of passes of the rolling / cooling pass is set, the cooling calculation is performed for all the rolling / cooling patterns, and the rolled material is predetermined from the rolling / cooling patterns for which the cooling calculation is performed. It is characterized by extracting a rolling / cooling pattern that gives a predetermined target temperature when the plate becomes thick, and adopting a rolling / cooling pattern that minimizes the rolling time among the extracted rolling / cooling patterns. Manufacturing method of thick steel plate.

[2] The method for manufacturing a thick steel sheet according to the above [1], wherein the thick steel sheet is manufactured by controlled rolling.

In the present invention, when manufacturing a thick steel sheet, a passing cooling type cooling facility is installed in the vicinity of a reversible rolling mill, and rolling is performed by a passing cooling type cooling facility while rolling with a reversible rolling mill according to a pass schedule. -When incorporating a cooling path (for example, when a thick steel sheet is manufactured by controlled rolling), it is possible to secure the target temperature and improve the rolling efficiency at the same time.

It is a figure which shows the rolling process which is the base in one Embodiment of this invention. It is a figure which shows the conventional rolling / cooling pattern determination logic. It is a figure which shows the rolling / cooling pattern determination logic in one Embodiment of this invention. It is a figure which compared the path schedule (exit side thickness, temperature) in the Example of this invention. It is a figure which compared the rolling time in the Example of this invention.

A method for manufacturing a thick steel plate according to an embodiment of the present invention will be described with reference to the drawings. Here, the case where the thick steel sheet is manufactured by controlled rolling will be described in mind.

FIG. 1 is a diagram showing a rolling process based on one embodiment of the present invention.

As shown in FIG. 1, in this rolling process, a heating furnace 1, a rolling mill (reversible rolling mill) 2, and cooling equipment (pass-through cooling type cooling equipment) arranged close to the downstream side of the rolling mill 2 are provided. It is equipped with 3.

In the passing cooling type cooling facility 3, the flow rate of the cooling water is constant, and the supply / stop (ON / OFF) of the cooling water is controlled. Further, the transport speed of the rolled material 10 can be adjusted within a predetermined range.

Then, the rolled material (thick steel plate) 10 extracted from the heating furnace 1 is rolled according to the following pass schedule.

First, between points A and B is a pass (normal pass) for performing normal rolling with the lossless rolling mill 2.

Next, between points B and C is a pass (rolling / cooling pass) in which the reversible rolling mill 2 rolls and the pass-cooling cooling facility 3 cools. At that time, when the rolled material 10 reaches a predetermined plate thickness (here, controlled rolling start plate thickness) at point C, the target temperature (here, controlled rolling start temperature) is reached. To do. An allowable range (for example, target temperature ± 3 ° C.) is provided for the target temperature.

Finally, between points C and D is a pass (normal pass: controlled rolling pass) in which the lossless rolling mill 2 performs normal rolling from the control rolling start plate thickness to the finished plate thickness.

Then, in the case of incorporating a rolling / cooling pass for cooling by the passing cooling type cooling facility 3 while rolling with the reversible rolling mill 2 into the pass schedule as described above (here, when the thick steel sheet is manufactured by controlled rolling). The procedure (determination logic) for determining the rolling / cooling pattern (number of rolling / cooling passes, presence / absence of rolling in the reversible rolling mill 2 in each rolling / cooling pass) is shown in FIG. Logic) is shown, and FIG. 3 shows a procedure (decision logic) in one embodiment of the present invention.

First, conventionally, as shown in FIG. 2, rolling / cooling patterns are arranged in order, calculation is started from the first rolling / cooling pattern, and control rolling is performed when the rolled material 10 reaches the control rolling start plate thickness. The calculation is completed when a rolling / cooling pattern (rolling / cooling pattern with good cooling) that can obtain a starting temperature of ± 3 ° C. is obtained. Then, the rolling / cooling pattern with good cooling was adopted.

Therefore, conventionally, the adopted rolling / cooling pattern is not always the rolling / cooling pattern that minimizes the rolling time.

On the other hand, in one embodiment of the present invention, the rolling / cooling pattern is determined as shown in FIG.

(S1) Cooling calculation is performed for all rolling / cooling patterns. If the number of rolling / cooling passes is large, the rolling time tends to be long. Therefore, an upper limit (for example, 8 passes) is set for the number of rolling / cooling passes.

(S2) Then, from all the rolling / cooling patterns for which the cooling calculation was performed in the above (S1), a temperature of the controlled rolling start temperature ± 3 ° C. can be obtained when the rolled material 10 reaches the controlled rolling start plate thickness. Extract the rolling / cooling pattern (rolling / cooling pattern with good cooling).

(S3) Next, the rolling time of each of the rolling / cooling patterns with good cooling extracted in (S2) above is calculated.

(S4) Then, based on the calculation result in (S3) above, a rolling / cooling pattern that minimizes the rolling time is adopted.

In this way, in this embodiment, when manufacturing a thick steel sheet, a pass-cooling type cooling facility is installed in the vicinity of the reversible rolling mill, and a pass-cooling type is performed while rolling with the reversible rolling mill according to the pass schedule. When incorporating a rolling / cooling path for cooling by a cooling facility (for example, when a thick steel sheet is manufactured by controlled rolling), it is possible to secure a target temperature and improve rolling efficiency at the same time.

As an embodiment of the present invention, when the rolling / cooling pattern is determined by the conventional determination logic shown in FIG. 2 for a thick steel sheet having the same dimensions and the same controlled rolling conditions (conventional example), the present invention shown in FIG. A comparison was made with the case where the rolling / cooling pattern was determined by the determination logic in one embodiment of the invention (example of the present invention).

FIG. 4 shows a diagram comparing the path schedule (exit side thickness, temperature) between the conventional example and the example of the present invention, and FIG. 5 shows a diagram comparing the rolling times of the conventional example and the example of the present invention.

As shown in FIG. 4, the rolling / cooling path is 6 passes in the conventional example, whereas the rolling / cooling path is 4 passes in the example of the present invention.

As shown in FIG. 5, the rolling time is 203 sec in the conventional example, whereas the rolling time is 190 sec, which is 13 sec shorter in the example of the present invention.

This confirmed the effectiveness of the present invention.

1 Elevated heating furnace 2 Rolling machine (reversible rolling machine)
3 Cooling equipment (pass-through cooling type cooling equipment)
10 Rolled material (thick steel plate)

Claims (2)

When manufacturing thick steel sheets, a pass-cooling cooling facility is placed close to the reversible rolling mill, and a rolling / cooling pass that cools with the passing-cooling cooling facility while rolling with the reversible rolling mill is included in the path schedule. In this case, the upper limit of the number of rolling / cooling passes is set to 8 and the rolling / cooling pattern (number of rolling / cooling passes, presence / absence of rolling in a reversible rolling mill in each rolling / cooling pass). , The cooling calculation is performed for all the passes from 1 to 8 times, and when the rolled material reaches a predetermined thickness from all the rolling / cooling patterns for which the cooling calculation has been performed, the predetermined target temperature is set. A method for manufacturing a thick steel plate, which comprises extracting a obtained rolling / cooling pattern and adopting a rolling / cooling pattern that minimizes the rolling time among the extracted rolling / cooling patterns. The method for manufacturing a thick steel sheet according to claim 1, wherein the thick steel sheet is manufactured by controlled rolling.

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