JP2009279637A - Method of commercializing passing residual material on hot rolling line - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of commercializing passing residual materials on a hot-rolling line, by which even when trouble occurs during the finish rolling of a preceding material on the hot-rolling line, the succeeding material is commercialized without making it the passing residual material, and remarkable drop of yield and downtime are prevented. <P>SOLUTION: In this method of commercializing the passing residual material on the hot-rolling line, when the trouble occurs on a part of finish rolling stands during the preceding material is rolled in the finish rolling on the hot rolling line, the reduction is released after the rolling of the preceding material in the finish rolling stand where the trouble occurs and also the succeeding material to be the passing residual material is rolled with usable finish rolling stands in which the trouble does not occur and, by changing the cooling pattern, the passing residual material is made into a new product which has thickness different from that of the original target sheet. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  In the hot rolling line for steel, the present invention carries out rolling of the succeeding material that becomes the remaining sheet through material on the line when troubles such as roll flaws occur during finish rolling of the preceding material. The present invention relates to a method for commercializing a remaining sheet material in a hot rolling line that can be used as a new product.

  FIG. 1 shows an example of a hot rolling line for steel. The hot rolling line A of steel is as long as several hundred meters in length, and a material to be rolled (slab) 1 having a thickness of about 150 mm to 300 mm, a length of about 10 m, and a width of about 700 mm to 2000 mm in a heating furnace 2 is a few hundred degrees. , And then, after performing width reduction with a width press 3 as necessary, a plurality of rough rolling mills 4 and a plurality of stands (7 in FIG. 1). It is a line that is rolled thinly to a thickness of about 1 mm to 25 mm by a finish rolling mill 5 comprising a stand), cooled by a cooling table (runout table) 7, wound in a coil shape by a coiler 8, and commercialized.

  These facilities are controlled by a control device 9 that is directly connected to each facility, a process computer 10 that controls them, and a business computer 11 that takes in product information and issues instructions.

  In the hot rolling line A, in order to efficiently perform rolling in a long line, a plurality of materials to be rolled (slabs) 1 are sequentially heated to a predetermined temperature in a heating furnace 2 and slabs that have reached the predetermined temperature are used. 1 is extracted on the line one after another, and a coiled product is manufactured by sequentially passing through the preceding material in the order of the roughing mill 4, the finishing mill 5, and the cooling table 7.

  Therefore, once rolling is started, a plurality of rolled materials are always on the hot rolling line, and the preceding rolled material (hereinafter referred to as the preceding material) is finish-rolled, A material to be rolled (hereinafter referred to as a subsequent material) is extracted from the heating furnace 2 and rides on a line, and some of the subsequent material may be subjected to rough rolling.

  In such a hot rolling line A, during the finish rolling of the preceding material, if there is a trouble such as roll wrinkles due to drawing or the like at a part of the rolling stand of the finishing mill 5, the following material is hot. It has already been on the line while being heated, and becomes a remaining plate. As a countermeasure for this trouble, for example, the roll of the stand where the roll flaw has occurred is replaced, but it takes about several minutes even if it is automated at this time. Compared to this, the time until the succeeding material is sent to the finish rolling mill 5 is remarkably short. Therefore, conventionally, when troubles such as roll wrinkles occur, rolling is temporarily stopped and the succeeding material remaining on the line is cut and eliminated as remaining board material, or the succeeding material is wrinkled. It is in a situation where it is necessary to choose either one of the products to be finished and rolled up with a roll as it is, and to give up the product as a remaining plate, and the subsequent material cannot be commercialized, resulting in a significant decrease in yield. When the succeeding material was cut, a significant downtime occurred, which was a big problem.

In addition, in the finish rolling of the hot rolling line, as a judgment of whether or not the succeeding material can be rolled, in Patent Document 1, in the finish continuous rolling, it is judged whether or not the continuous rolling can be continued by the limit of the running thickness change control. However, a method has been proposed in which continuous rolling is stopped when the finish sheet thickness of the succeeding material exceeds the control limit.This is the case when all the stands of the finishing mill are rolled in a steady state. Assuming that, as described above, there is no assumption about the case where troubles such as generation of roll wrinkles occur in some of the stands of the finish rolling mill.
JP-A-11-267708

  As described above, once a trouble occurs in the finish rolling of the preceding material in the conventional hot rolling line, the subsequent material already on the line has to be abandoned, and the remaining plate is left behind. As a material, it can only be cut and discarded as scrap, or it can be rolled, cooled, rolled up and discarded with cocoons, resulting in significant yield reduction and downtime. It was desired.

  In view of the above circumstances, in the present invention, even if a trouble occurs during finish rolling of a preceding material in a hot rolling line, the subsequent material can be commercialized without passing through the remaining material, resulting in a significant decrease in yield. It is an object of the present invention to provide a method for producing a remaining sheet material in a hot rolling line that can prevent downtime.

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

  [1] In the finish rolling of the hot rolling line, when a trouble occurs in some finish rolling stands while rolling the preceding material, the finishing rolling stand in which the trouble has occurred releases the reduction after rolling the preceding material. In addition, the hot rolling line is characterized in that the succeeding material, which will be the remaining sheet material, is rolled on a usable finish rolling stand that does not cause any troubles, resulting in a new product different from the original target sheet thickness. To commercialize left-over sheet material in Japan.

  [2] Predetermining the finishing plate thickness when rolling on a usable finish rolling stand that does not cause any trouble, and cooling the target finishing temperature and the cooling table after finish rolling for each finishing plate thickness and steel type Prepare a pattern, and when trouble occurs, set the finishing plate thickness of the succeeding material, the target finishing temperature, and the cooling pattern after finish rolling to perform rolling and cooling of the succeeding material. The method of commercializing a left-over sheet material in a hot rolling line as described in [1] above.

  According to the present invention, in the hot rolling line, even if a trouble occurs during the finish rolling of the preceding material, it is possible to reliably commercialize the succeeding material that will be the remaining material of the passing plate, and to significantly reduce the yield and downtime. Can be prevented.

  Hereinafter, the present invention will be described in detail.

  If there is a problem such as roll flaws occurring at some of the stands of the finish rolling mill during the finish rolling of the preceding material on the hot rolling line, the succeeding material will remain on the line at a high temperature as the remaining sheet material. .

  Conventionally, since rolling was temporarily stopped at the stage where there was a trouble as described above, the subsequent material remaining on the line was inevitably cut off as a remaining plate material, or the subsequent material was rolled. I had to choose between finishing and rolling with rolls with ridges and giving up the product as a remaining plate.

  Therefore, as a result of intensive studies on this problem, the present inventors have focused on the finish rolling method and found a method for relieving and commercializing the succeeding material as the remaining sheet material.

  That is, if the stand where the roll wrinkles are used is used as it is, the roll wrinkles are transferred to the material to be rolled and do not become a product. Therefore, the stand where the roll wrinkles are generated is opened so as not to be reduced, and a method of rolling with another stand without the roll wrinkles is adopted, thereby making it possible to manufacture a product without wrinkles. However, since the number of stands that can be used for rolling is reduced at that time, the total rolling reduction in finish rolling is lower than usual, and as a result, the thickness of the succeeding material after finish rolling is the original target plate. Thicker than thickness. Therefore, it is possible to commercialize the following material not by the original product order but by directing it to another product order having a thick plate thickness.

  As a result, even if a trouble occurs in the preceding material, the succeeding material can be relieved as a product with a different thickness, so the yield can be remarkably improved, and the downtime for cutting the succeeding material as the remaining sheet material does not occur. .

  In addition, when making the following material a new product with a large plate thickness, even if the steel components are the same, if the cooling pattern after finish rolling (cooling pattern on the cooling table) remains the same, the plate thickness It has been found that there are many cases where the structure of the material to be rolled changes due to a slow cooling rate due to the increase in thickness, and the material characteristics may not be ensured as a product.

  In other words, the material properties of the material to be rolled are mainly determined by the cooling pattern after finish rolling, but as described above, the subsequent material after the occurrence of a trouble has a thick plate thickness, and the cooling pattern after finish rolling is left as it is. And cooling may be insufficient. As a result, the coiling temperature becomes high, and the material properties of the following material are different from the target product.

  Therefore, in order to cope with this problem, the present inventors have made it possible to cool with a cooling pattern suitable for the succeeding material after the trouble occurs.

  In other words, it is difficult to specify a stand where troubles such as rolls occur during rolling of the preceding material. Therefore, it is assumed that there are various troubles in advance, and a stand where trouble does not occur at that time. The finished plate thickness in the case of using and rolling is determined, and the target finish temperature and the cooling pattern after finish rolling according to the finished plate thickness and the steel type are determined as condition settings. When troubles such as roll wrinkles occur, after the preceding material is rolled, the stand where the trouble such as roll wrinkles has occurred is identified, and before the succeeding material is subjected to finish rolling, or the leading edge of the succeeding material is on the finish rolling exit side. Before arriving, applying the above condition settings, setting the finishing plate thickness of the succeeding material, the target finishing temperature, the cooling pattern after finish rolling, and rolling and cooling the succeeding material accordingly . These series of operations can be automated by a computer.

  In the hot rolling line A shown in FIG. 1, a 1.8 mm thin material was manufactured from a 200 mm thick slab 1. The slab 1 was sequentially extracted from the heating furnace 2 and rolled in a state where a plurality of materials to be rolled are on the line. At that time, when roll wrinkles occurred during finish rolling of the preceding material, the following material on the line was processed according to the following examples of the present invention and the conventional example.

(Invention Example 1)
In order to be able to cope with roll wrinkles occurring in any of the stands of finish rolling in advance, the reduction pattern and finish thickness when the roll wrinkle generation stand is released and rolled with the remaining stands, and Set the cooling pattern on the cooling table according to the finish thickness and steel type, input the contents to the computer, and automatically change the setting of the rolling and cooling conditions of the succeeding material according to the occurrence of roll flaws I made it.

  And during finishing rolling of the preceding material, roll wrinkles were generated in the sixth stand and the seventh stand by drawing, so that the reduction of these stands was released and the first stand to the fifth stand where no roll wrinkles were generated. , The thickness of the finish rolling delivery side was changed from the original 1.8 mm to 6 mm, and the succeeding material was rolled. The cooling pattern on the cooling table was also changed to an optimum pattern corresponding to the increase in the finished plate thickness and the steel type of the following material.

  As a result, the succeeding material, which should be the remaining plate material in the past, can be made into a new product with a finished plate thickness of 6 mm according to the present invention, and a significant reduction in yield and downtime can be prevented.

(Invention Example 2)
In advance, set the rolling pattern and finish thickness for the roll roll generation stand in the final rolling and release the roll roll in the remaining stands, and input the contents to the computer to roll the roll roll during the preceding material rolling. The setting of the rolling condition of the succeeding material can be changed automatically according to the occurrence of

  Then, during finishing rolling of the preceding material, roll wrinkles occurred in the third stand due to a trouble of passing through the squeezing. Therefore, the reduction of the third stand was released, and the first stand and the second stand where no roll wrinkles were generated. Using the fourth stand to the sixth stand, the thickness of the finish rolling exit side was changed from 1.8 mm to 2.3 mm, and the succeeding material was rolled. Note that the cooling pattern on the cooling table was sufficient to ensure material characteristics because the degree of change in the plate thickness was small, and was left as it was.

  As a result, the succeeding material, which should be the remaining sheet material in the past, can be made into a new product with a finished sheet thickness of 2.3 mm according to the present invention, and a significant reduction in yield and downtime can be prevented. It was.

(Conventional example 1)
During finishing rolling of the preceding material, roll wrinkles occurred in the 6th and 7th stands due to drawing, so the rolling was temporarily stopped and the subsequent material remaining on the line was gas cut as the remaining plate material, Discarded as scrap. Meanwhile, downtime due to line stoppage occurred significantly.

(Conventional example 2)
During finishing rolling of the preceding material, roll wrinkles due to drawing occurred in the second stand, but in order to avoid downtime due to processing of the following material, the subsequent material was rolled as it was. As a result, the roll ridges of the second stand were transferred over the entire length of the succeeding material after the finish rolling, and the entire length of the succeeding material was discarded as scrap as the remaining plate material.

  As described above, when trouble occurs during finish rolling of the preceding material in the hot rolling line, in the conventional example, the succeeding material has to be scrapped as the remaining sheet material, and the yield is remarkably reduced and drastically reduced. There was also a case where downtime came.

  On the other hand, in the example of the present invention, the succeeding material can be surely commercialized, it is possible to prevent a significant decrease in the yield, and no downtime is caused, and the effect is remarkably good. .

It is a figure which shows an example of a hot rolling line.

Explanation of symbols

A: Hot rolling line 1: Rolled material (slab)
2: Heating furnace 3: Width press 4: Rough rolling mill 5: Finish rolling mill 7: Cooling table (runout table)
8: Coiler 9: Control device 10: Process computer 11: Business computer

Claims (2)

  In the finish rolling of the hot rolling line, when trouble occurs in some finish rolling stands during rolling of the preceding material, the finishing rolling stand in which the trouble has occurred releases the reduction after rolling the preceding material, and passes The subsequent material, which is the remaining sheet material, is rolled in a usable finish rolling stand that does not cause any troubles, and is passed through a hot rolling line, which is a new product that differs from the original target sheet thickness. A method for commercialization of board residue.   Predetermined finish plate thickness when rolling on a usable finish rolling stand that does not have any troubles is prepared, and target finish temperature and cooling pattern on the cooling table after finish rolling are prepared for each finish plate thickness and steel type In addition, when trouble occurs, the finish sheet thickness, target finish temperature, and cooling pattern after finish rolling are set based on the trouble, and the subsequent material is rolled and cooled. The method for commercializing the remaining sheet material in the hot rolling line according to claim 1.

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