JP6805993B2 - Rolling method and manufacturing method of thick steel sheet - Google Patents

Description

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

In general, rolling a thick steel sheet refers to rolling a steel sheet having a thickness of 4.5 mm or more after finishing rolling.

Normally, as shown in FIG. 1, the path schedule for rolling a thick steel sheet is a reduction amount constraint path based on the restriction of the reduction amount per pass (engagement angle to the rolling roll) and a motor of the rolling mill. Motor torque limit path based on torque limit, rolling load limit path based on rolling machine load (rolling load) limit, and shape constraint to ensure flatness (shape) of thick steel sheet after finish rolling It consists of a path.

Among them, as for the shape constraint path, a method of creating a path schedule so that the plate crown ratio is constant has been conventionally performed (see, for example, Patent Document 1).

JP-A-2007-130667

As described above, conventionally, since the shape constraint path is created based on the idea that the plate crown ratio is constant, the profile (wear, thermal expansion) of the roll during rolling that affects the plate crown is determined. It is necessary to grasp with high accuracy.

However, since the wear and thermal expansion of the roll during rolling cannot be actually measured, it is calculated by a calculation model or the like, but the wear and thermal expansion of the roll during rolling change variously depending on the rolling history after the roll rearrangement. Therefore, it is difficult to grasp it accurately.

As a result, conventionally, the thinner the finished plate thickness of the thick steel plate and the wider the finished plate width (for example, the finished plate thickness is 9 mm or less and the finished plate width is 3000 mm or more), the thicker the steel plate after finishing rolling is subjected to plate wave (for example). Distortion) was likely to occur, and it was difficult to ensure stable flatness.

At that time, if the amount of distortion generated is small (for example, within the allowable tolerance), online processing is sufficient, but if the amount of distortion generated is large (for example, exceeding the allowable tolerance), offline. (For example, cold press straightening) is required.

The present invention has been made in view of the above circumstances, and when rolling and manufacturing a thick steel sheet, a thick steel sheet capable of stably ensuring the flatness of the thick steel sheet after the finish rolling is completed. It is an object of the present invention to provide a rolling method and a manufacturing method of the above.

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

[1] When rolling a thick steel plate, four items of rolling conditions (finished plate thickness, finished plate width, roll chance, steel type), shape constraint path, and shape constraint path are used for each rolled material that has been rolled so far. When creating a strain database that stores the amount of strain after finishing rolling and creating a path schedule for the rolling material to be rolled from now on, among the rolling performance materials stored in the strain database, 4 Among the rolling performance materials whose rolling conditions (finished plate thickness, finishing plate width, roll chance, steel grade) are similar to the planned rolling material, the shape constraint of the rolling performance material with the smallest amount of strain after finishing rolling A method for rolling a thick steel plate, wherein the path is a shape-constrained path for the material to be rolled.

[2] With respect to the rolling performance materials stored in the strain database, classifications are provided for each of the four rolling conditions, and the amount of strain after the finish rolling is the most for each combination of the four rolling condition classifications. A rolling record material with a small rolling value was selected, and was selected as having the smallest amount of strain after finishing rolling in the combination of four rolling condition categories that match the four rolling condition combinations of the planned rolling material. The method for rolling a thick steel plate according to the above [1], wherein the shape-constrained path of the actual rolling material is the shape-constrained path of the material to be rolled.

[3] Similar ranges are set for each of the four rolling conditions of the planned rolling material, and the rolling results materials that fall within all of the similar ranges are extracted from the rolling results materials stored in the strain database. Then, among the extracted rolling performance materials, the rolling performance material with the smallest amount of strain after finishing rolling is selected, and the shape constraint path of the selected rolling performance material is set as the shape constraint path of the planned rolling material. The method for rolling a thick steel plate according to the above [1].

[4] The heating temperature is added to the four rolling conditions (finished plate thickness, finished plate width, roll chance, steel type), and the five rolling conditions (finished plate thickness, finished plate width, roll chance, steel type, etc.) The method for rolling a thick steel sheet according to any one of [1] to [3] above, wherein the temperature is set to (heating temperature).

[5] The method for rolling a thick steel sheet according to any one of [1] to [4], wherein the finished plate thickness of the material to be rolled is 9 mm or less and the finished plate width is 3000 mm or more.

[6] A method for producing a thick steel sheet, which comprises producing a thick steel sheet by using the method for rolling a thick steel sheet according to any one of the above [1] to [5].

In the present invention, when rolling and manufacturing a thick steel sheet, the flatness of the thick steel sheet after the finish rolling can be stably ensured.

It is a figure which shows the path schedule at the time of rolling a thick steel plate. It is a conceptual diagram of the thick steel sheet rolling system in embodiment of this invention. It is a figure which compared the flatness of the thick steel plate in the Example of this invention. It is a figure which compared the path schedule in the Example of this invention. It is a figure which compared the correction process occurrence rate in the Example of this invention.

An embodiment (Embodiments 1 and 2) of the method for rolling a thick steel sheet of the present invention will be described.

FIG. 2 is a conceptual diagram of the thick steel sheet rolling system 10 according to the embodiment of the present invention (Embodiments 1 and 2).

As shown in FIG. 2, the thick steel sheet rolling system 10 in this embodiment (Embodiments 1 and 2) includes a rolling process controller 11 that controls a rolling line, a rolling file server 12 connected to the rolling process controller 11, and a rolling file server. It includes a strain database 13 stored in 12, a shearing processor 14 that controls a shearing line located downstream of the rolling line, and a strain gauge (flatness meter) 15 installed on the shearing line.

[Embodiment 1]
In the first embodiment, when rolling a thick steel sheet, a path schedule for the material to be rolled is created by the following procedure, and the material to be rolled is rolled.

(S1) First, for each rolled material that has been rolled so far, four items of rolling conditions (finished plate thickness, finished plate width, roll chance, steel type), a path schedule (at least, a shape constraint path), and A strain database 13 containing the amount of strain after finishing rolling is created.

Here, the roll chance is the number of rolled materials rolled after the roll is rearranged until the rolling material is rolled.

The amount of strain after finishing rolling is the measurement result of a strain gauge (flatness meter) 15 installed on the shearing line, and the amount of strain (L / m) per unit length in the longitudinal direction of the actual rolling material. ) And the amount of strain (C / m) per unit width in the width direction.

(S2) Next, for the rolling performance materials stored in the strain database 13, classifications are provided for each of the four rolling conditions (finished plate thickness, finished plate width, roll chance, steel type).

For example, it is as follows.

Classification of finished plate thickness: 7 mm or less, 7 mm or more and 9 mm or less, ...
Finishing plate width classification: 2000 mm or less, 2000 mm or more and 3000 mm or less, ...
Roll chance classification: 100 or less, 100 or more and 200 or less, ...
Classification of steel type: Carbon equivalent Ceq 0.4% or less, 0.4% or more and 0.5% or less, ...

(S3) Next, for each combination of the four items of rolling condition classification provided in (S2) above, the rolling performance material having the smallest amount of strain after finishing rolling is selected.

For example, for a combination of four rolling conditions, the finishing plate thickness is 7 mm or less, the finishing plate width is 2000 mm or more and 3000 mm or less, the roll chance is 100 or less, and the carbon equivalent is Ceq 0.4% or less, the strain after the finishing rolling is the most. The rolling performance material A is selected as the rolling performance material with a small amount.

(S4) Then, when creating the path schedule of the planned rolling material, a combination of four rolling condition classifications matching the combination of the four rolling conditions of the planned rolling material is selected, and in the above (S3). , The rolling performance material selected as having the smallest amount of strain after finishing rolling in the combination of the four rolling condition classifications is called.

For example, if the rolling conditions of the four items of the material to be rolled are a combination of a finished plate thickness of 6.4 mm, a finished plate width of 2600 mm, 80 roll chances, and a carbon equivalent of Ceq 0.4%, it is illustrated in (S3) above. Since it matches the combination of the classifications of the four rolling conditions, the rolling performance material A is called as the rolling performance material having the smallest strain amount after the finish rolling in that combination.

(S5) Then, the shape constraint path of the actual rolling material called in (S4) above is set as the shape constraint path of the material to be rolled.

(S6) Regarding the path on the upstream side of the shape constraint path, the rolling conditions of the four items of the planned rolling material are not necessarily the same as those of the actual rolling material called in (S4) above. Create a rolling reduction constraint path based on the rolling roll constraint, create a motor torque limiting path based on the rolling mill motor torque limit, and create a rolling mill load (rolling load). ), Create a rolling load limit path.

(S7) The planned rolling material is rolled according to the path schedule created as described above. The obtained data is stored in the distortion database 13.

In this way, in the first embodiment, when rolling a thick steel plate, a rolling performance material having rolling conditions similar to the rolling conditions (finished plate thickness, finished plate width, roll chance, steel type) of the material to be rolled. Since the shape-constrained path of the rolled material having the smallest strain amount is set to the shape-constrained path of the material to be rolled, the flatness can be stably ensured.

[Embodiment 2]
In the second embodiment, when rolling a thick steel sheet, a path schedule for the material to be rolled is created by the following procedure, and the material to be rolled is rolled.

(P1) First, for each rolled material that has been rolled so far, four items of rolling conditions (finished plate thickness, finished plate width, roll chance, steel type), path schedule (at least, shape constraint path), and A strain database 13 containing the amount of strain after finishing rolling is created.

Here, the roll chance is the number of rolled materials rolled after the roll is rearranged until the rolling material is rolled.

The amount of strain after finishing rolling is the measurement result of a strain gauge (flatness meter) 15 installed on the shearing line, and the amount of strain (L / m) per unit length in the longitudinal direction of the actual rolling material. ) And the amount of strain (C / m) per unit width in the width direction.

(P2) Then, when creating the path schedule of the planned rolling material, the rolling conditions of the four items of the planned rolling material (finished plate thickness tmm, finished plate width B mm, roll chance N pieces, steel type (for example, carbon equivalent) Similar ranges (finished plate thickness t ± Δt mm, finished plate width B ± ΔB mm, roll chance N ± ΔN, steel grade Ceq ± ΔCeq) are provided in each of Ceq)).

(P3) Next, from the rolling performance materials stored in the strain database 13, the rolling performance materials that fall within all of the similar ranges provided in (P2) above are extracted.

(P4) Next, among the rolling performance materials extracted in (P3) above, the rolling performance material having the smallest amount of strain after finishing rolling is selected.

(P5) Then, the shape constraint path of the rolling performance material selected in the above (P4) is set as the shape constraint path of the rolling material to be rolled.

(P6) Regarding the path on the upstream side of the shape constraint path, the rolling conditions of the four items of the material to be rolled are not necessarily the same as the actual rolling material selected in (P4) above. A rolling reduction constraint path is created based on the rolling reduction amount (engage angle to the rolling roll), a motor torque limiting path is created based on the rolling mill motor torque limitation, and the rolling mill load (rolling) is created. Create a rolling load limit path based on the load limit.

(P7) The planned rolling material is rolled according to the path schedule created as described above. The obtained data is stored in the distortion database 13.

In this way, in the second embodiment, when rolling a thick steel plate, a rolling performance material having rolling conditions similar to the rolling conditions (finished plate thickness, finished plate width, roll chance, steel type) of the material to be rolled. Since the shape-constrained path of the rolled material having the smallest strain amount is set to the shape-constrained path of the material to be rolled, the flatness can be stably ensured.

In the first and second embodiments, the heating temperature is added to the four rolling conditions (finished plate thickness, finished plate width, roll chance, steel type), and the five rolling conditions (finished plate thickness, finished plate width, etc.) Roll chance, steel type, heating temperature) is more preferable.

Then, if the above-described first and second embodiments are applied to rolling and manufacturing of a thick steel plate whose flatness is difficult to secure (for example, a finished plate thickness of 9 mm or less and a finished plate width of 3000 mm or more), a great effect can be obtained. Can be done.

Examples of the present invention will be described.

Here, the case where the shape constraint path is created based on the idea of keeping the plate crown ratio constant as in the conventional case is taken as a conventional example, and the case where the shape constraint path is created based on the above-described first embodiment of the present invention is the present case. This is an example of the invention.

As for the rolled material, the finished plate thickness was 6 mm and the finished plate width was 3000 mm.

FIG. 3 is a diagram comparing the flatness after finishing rolling between the conventional example and the example of the present invention.

In the conventional example, a large distortion (medium wave) was often generated as shown in FIG. 3 (a), but in the example of the present invention, as shown in FIG. 3 (b), a good flatness (flatness) was generated. ) In many cases.

FIG. 4 is a diagram comparing changes in the path schedule between the rolled materials under similar rolling conditions between the conventional example and the example of the present invention.

In the conventional example, as shown in FIG. 4A, even if the rolled material has similar rolling conditions, the pass schedule often changes greatly for each rolled material and a large strain is generated in many cases. In the example, as shown in FIG. 4B, there was little change in the path schedule between the rolled materials under similar rolling conditions, and stable and good flatness could be obtained.

As a result, as shown in FIG. 5, the rate at which the offline correction process occurred (correction process occurrence rate) was significantly reduced to 33 in the example of the present invention when the conventional example was set to 100.

As a result, the effectiveness of the present invention could be confirmed.

10 Thick steel sheet rolling system 11 Rolling process controller 12 Rolling file server 13 Strain database 14 Shear process controller 15 Strain meter (flatness meter)

Claims (6)

When rolling a thick steel plate, four items of rolling conditions (finished plate thickness, finished plate width, roll chance, steel type), shape constraint path, and finish rolling are completed for each rolled material that has been rolled so far. A strain database containing the subsequent strain amount is created, and the rolling performance materials stored in the strain database are classified into each of the four rolling conditions, and the rolling conditions of the four items are set. For each combination of categories, select the rolling performance material with the smallest amount of strain after finishing rolling.
When creating a path schedule for the rolling material to be rolled from now on, select a combination of four rolling condition categories that match the rolling conditions of the rolling material.
The feature is that the shape-constrained path of the rolling performance material with the smallest amount of strain after finishing rolling selected for the combination of the four selected rolling condition classifications is used as the shape-constrained path of the planned rolling material. Rolling method for thick steel sheets. When rolling a thick steel plate, four items of rolling conditions (finished plate thickness tmm, finished plate width B mm, roll chance N, carbon equivalent Ceq ) ) and shape for each rolled material that has been rolled so far. Create a strain database that stores the constraint path and the strain amount after finishing rolling.
Similar ranges (finished plate thickness t ± Δt mm, finished plate width B ± ΔB mm, roll chance N ± ΔN, carbon equivalent Ceq ± ΔCeq, however, Δtmm, respectively, for each of the four rolling conditions of the material to be rolled to be rolled. ΔBmm, ΔN lines, and ΔCeq are preset numerical values), and from the rolling performance materials stored in the strain database, rolling performance materials that fall within all of the similar ranges are extracted.
Among the extracted rolling performance materials, the rolling performance material with the smallest amount of strain after finishing rolling is selected.
A method for rolling a thick steel sheet, characterized in that the shape-constrained path of the selected rolling performance material is the shape-constrained path of the material to be rolled. The heating temperature is added to the four rolling conditions (finished plate thickness, finished plate width, roll chance, steel type), and the five rolling conditions (finished plate thickness, finished plate width, roll chance, steel type, heating temperature). The method for rolling a thick steel sheet according to claim 1 , wherein the thick steel sheet is rolled. The heating temperature is added to the four rolling conditions (finished plate thickness, finished plate width, roll chance, carbon equivalent Ceq), and the five rolling conditions (finished plate thickness, finished plate width, roll chance, carbon equivalent Ceq) are added. The method for rolling a thick steel sheet according to claim 2, wherein the temperature is set to (heating temperature). The method for rolling a thick steel plate according to any one of claims 1 to 4 , wherein the finished plate thickness of the material to be rolled is 9 mm or less and the finished plate width is 3000 mm or more. A method for producing a thick steel sheet, which comprises producing the thick steel sheet by using the method for rolling a thick steel sheet according to any one of claims 1 to 5 .

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