JP5962923B2 - Thick plate manufacturing method - Google Patents

Description

  The present invention relates to a method of manufacturing a thick plate. Specifically, the thickness of the thick plate is intended to be rolled when a plurality of products having different plate thickness guarantee specifications (conditions) are taken from one rolled thick plate. Is related to the method of determining.

  Except for specific products such as materials for line pipes, the current situation is that the contents of orders are extremely diverse in terms of steel type, dimensions, required characteristics, order quantity, delivery date, and the like. Therefore, when designing the material for thick plates, we will create a production lot that is most advantageous in terms of productivity and cost, while satisfying a wide variety of orders and considering various manufacturing constraints. It is necessary to design the minimum necessary materials. Specifically, the quality of a single product order is designed based on the required quality, manufacturing process capability, etc., the results are grouped, and the plate is taken from a thick plate taking into account the product dimensions. Furthermore, considering the yield and the like, the material (slab) weight, which is a rolling material, casting conditions, and the like are determined (for example, see Patent Document 1).

  In deciding the plate removal from the thick plate, from the viewpoint of improving productivity and reducing manufacturing cost, the steel grade and required characteristics are the same from the above order, and the plate thickness is the same or approximated as much as possible. It is important to group orders and bring the dimensions of the planks to be trimmed close to the maximum dimensions (width and length) determined from the specifications of the manufacturing equipment. As a result, products extracted from one thick plate after rolling include products with different product thicknesses. Therefore, when rolling a thick plate that collects products of various orders as described above, it is possible to determine the thickness to be rolled, that is, the “thickness for rolling” so that all orders are satisfied. It is necessary (see, for example, Patent Document 2). The grouping of the orders and the determination of the thickness for rolling are usually performed automatically using a computer.

  By the way, most plate thickness specifications of conventional plate products are composed of a product thickness (also referred to as “nominal thickness”) and a thickness tolerance (upper limit thickness, lower limit thickness) with respect to the product thickness. This sheet thickness specification is a content that guarantees that the minimum value of the actual sheet thickness of the product is equal to or greater than the lower limit thickness thickness tolerance. Therefore, this sheet thickness specification is hereinafter referred to as “lower limit thickness guarantee”. . The lower limit thickness of the thickness tolerance is also simply referred to as “tolerance lower limit thickness”.

  FIG. 1 is a diagram for explaining a method for determining a rolling target thickness of a thick plate when products of orders A, B and C having different product thicknesses and tolerance lower limit thicknesses are taken from a single thick plate. . The method of determining the thickness intended for rolling is the “thickness of product” and “thickness tolerance lower limit thickness” of the thickest product thickness and “thickness tolerance lower limit thickness” of the product thickness and tolerance lower limit thickness in orders A, B and C. In this case, in order to ensure that the minimum thickness of the actual sheet thickness is equal to or greater than the above-mentioned representative tolerance lower-limit thickness, an additional thickness α is added to the above-mentioned representative tolerance lower-limit thickness in consideration of sheet thickness fluctuations during rolling, etc. . Note that the larger the added thickness α is, the more advantageous it is to set it to the representative tolerance lower limit thickness or more, but if it is too large, the actual sheet thickness will increase, exceeding the upper limit thickness of the sheet thickness tolerance, or the required material weight However, it is important not to make it too large.

  On the other hand, in recent years, from the standpoint of improving the safety of the steel sheet itself, in addition to the above "guaranteed minimum thickness guarantee", there is an order that requires the actual average sheet thickness to be equal to or greater than the product thickness. There is a tendency to increase. Hereinafter, this plate thickness specification is referred to as “product thickness guarantee”.

  FIG. 2 shows the target thickness of rolling of the above-mentioned thick plate when the products of orders A, B and C having different product thicknesses and tolerance lower limit thicknesses are required from a single thick plate, which requires “product thickness guarantee”. It is a figure explaining the determination method. As in FIG. 1, among the product thicknesses and tolerance lower limit thicknesses in orders A, B, and C, this method has the thickest product thickness as “representative product thickness” and the thickest tolerance lower limit thickness as “representative tolerance lower limit thickness”. This is a method of adding an additional thickness β in consideration of fluctuations in the plate thickness during rolling to the representative product thickness so that the average thickness of the actual plate thickness is surely equal to or greater than the representative product thickness. It is important that the added thickness β is not too large for the same reason as the added thickness α. In addition, the above-mentioned additional thickness β is smaller than the additional thickness α when the lower limit thickness is guaranteed because the average thickness may be equal to or greater than the product thickness even if the actual thickness is partially below the product thickness. It's okay.

Japanese Patent Laid-Open No. 06-149850 JP 2006-281252 A

  As described above, the target thickness for rolling differs between the order for obtaining the “lower limit thickness guarantee” and the order for obtaining the “product thickness guarantee”. Therefore, if the product collected from a single plate consists only of an order that requires a “lower limit thickness guarantee” or only an order that requires a “product thickness guarantee”, the target thickness of the plate is determined. There is no problem in doing. However, in the current situation where there are a wide variety of orders, there is no choice but to make an order for "Lower Thickness Guarantee" and an order for "Product Thickness Guarantee" into one group, that is, from one rolled plate. There are many cases in which it is necessary to collect products with a “Lower Thickness Guarantee” and “Product Thickness Guarantee”.

  Conventionally, in such a case, as can be seen by comparing FIG. 1 and FIG. 2, if the order is the same representative product thickness and the representative tolerance lower limit thickness, an order for “Product Thickness Guarantee” to increase the thickness intended for rolling. Priority was given to the target thickness, and this was set as the target thickness at the time of the rolling order. However, in the above method, when various orders with different plate thickness specifications are grouped, depending on the combined plate thickness specification, the thickness intended for rolling may be increased more than necessary, or the plate thickness specifications of all orders may not be satisfied. To do.

The present invention developed to solve the above problems is a product that guarantees that the minimum thickness of the actual plate thickness is equal to or greater than the tolerance lower limit thickness of the product plate thickness for a plurality of ordered products obtained from one thick plate. In addition to the above, in addition to the above, when the product group that guarantees that the average thickness of the actual sheet thickness is equal to or greater than the product thickness, the minimum thickness of the actual sheet thickness is equal to or greater than the tolerance lower limit thickness of the product thickness Representative products of the product group that guarantees that the minimum thickness of the actual sheet thickness is equal to or greater than the tolerance lower limit thickness of the product thickness and that the average thickness of the actual sheet thickness is equal to or greater than the product thickness This is a method for manufacturing a thick plate, characterized in that the target thickness for provisional rolling of each group is obtained from the thickness and the representative tolerance lower limit thickness, and the thicker one of them is set as the target thickness for rolling in the rolling instruction for the thick plate. Here, the representative product thickness and is the thickest product thickness within one product group, also, the above-mentioned representative tolerance lower limit thickness refers to the thickest lower tolerance thickness within one product group.

  The present invention developed to solve the above problems is a product group that guarantees that the minimum thickness of the actual sheet thickness is equal to or greater than the lower limit tolerance of the product thickness for a plurality of products that are plated from one thick plate, In addition to the above, when configured with a product group that guarantees that the average thickness of the actual sheet thickness is equal to or greater than the product thickness, the minimum thickness of the actual sheet thickness is guaranteed to be equal to or greater than the tolerance lower limit thickness of the product thickness. In addition to the above, the provisional rolling target thickness of each group is obtained from the representative product thickness and the representative tolerance lower limit thickness of each product group that guarantees that the average thickness of the actual sheet thickness is equal to or greater than the product thickness. A thick plate manufacturing method is characterized in that the thicker one is set as a rolling target thickness in the rolling instruction for the thick plate. Here, the representative product thickness means the thickest product thickness in each product group, and the representative tolerance lower limit thickness means the thickest tolerance lower limit thickness in each product group.

  According to the present invention, it is possible to optimize the rolling target thickness in the case where a plurality of products having different plate thickness guarantee conditions are cut from a single rolled plate, so that the weight of the rolling material (slab) can be reduced. And manufacturing costs can be reduced. In addition, since the thickness targeted for rolling can be set thin, a margin for the upper limit value of the thickness tolerance is increased, and occurrence of defects due to deviation of the upper limit value of the thickness tolerance can be reduced.

It is a figure explaining the method of determining the rolling aim thickness when it is requested | required that the minimum value of track | truck thickness is more than the lower limit thickness of thickness tolerance. It is a figure explaining the method of determining the rolling target thickness when it is requested | required that the average thickness of a performance board thickness is more than product thickness. It is a figure explaining the method of determining the conventional rolling target thickness in the case of extract | collecting the product which requests | requires "lower limit thickness guarantee" and the product which asks for "product thickness guarantee" from one rolled thick board. It is a figure explaining the method of determining the rolling target thickness of this invention in the case of extract | collecting the product which requests | requires "lower limit thickness guarantee" and the product which asks for "product thickness guarantee" from one rolled thick board.

As described above, when collecting only products with a “lower limit thickness guarantee” that requires that the minimum value of the actual sheet thickness be equal to or greater than the lower limit thickness thickness tolerance from one rolled sheet, or rolled In the case of collecting only “Product Thickness Guarantee” products that require that the average thickness of the actual sheet thickness is equal to or greater than the product thickness from one thick plate, the method for determining the target rolling thickness of the thick plate is The method described in FIG. 1 or FIG.
In addition, in the case where a “lower limit thickness guaranteed” product and a “product thickness guaranteed” product are collected from one rolled plate, conventionally, a method of determining a rolling target thickness in “product thickness guarantee”, that is, The method of adding the additional thickness β to the representative product thickness was employed. The reason for this is that, as can be seen by comparing FIGS. 1 and 2, with the same product thickness, the “product thickness guarantee” is thicker than the “lower limit thickness guarantee”, and the target thickness for rolling is thicker.

However, the inventors' experience has shown that in situations where the plate thickness specifications are different, not all of the above are possible depending on the plate thickness specifications of the orders to be combined.
Fig. 3 shows the problem of the conventional method for determining the thickness to be used for rolling when the products collected from a single plate consist of an order group that requires "lower limit thickness guarantee" and an order group that requires "product thickness guarantee". This explains the point. In FIG. 3, the case where the number of orders in each order group is 1 is described for the sake of simplicity.

  In case 1, the representative product thickness of the order group for which product thickness guarantee is required is larger than the representative product thickness of the order group for which lower limit thickness guarantee is required, and the target rolling thickness of the order group for which product thickness guarantee is required is the lower limit. This shows the case where the thickness is larger than the target rolling thickness of an order group that requires a thickness guarantee. In this case, the representative product thickness is the product thickness of the order group for which product thickness guarantee is required. Therefore, there is no problem because the target thickness of the rolling plate is the target group for which the product thickness guarantee is required.

  On the other hand, in case 2, contrary to case 1, the representative product thickness of the order group requiring product thickness guarantee is thinner than the representative product thickness of the order group requiring minimum thickness guarantee, and the product thickness guarantee This shows a case where the target rolling thickness of the order group that is required to be less than the target thickness of the order group that is required to guarantee the lower limit thickness. In this case, the representative product thickness is the product thickness of the order group for which the guarantee of the lower limit thickness is required, and the target thickness for rolling the steel sheet is determined based on the above representative product thickness. Become thicker. Therefore, there arises a problem that the material weight needs to be increased accordingly.

  In case 3, the representative product thickness of the order group requiring product thickness guarantee is thinner than the representative product thickness of the order group requiring minimum thickness guarantee, and conversely, the target thickness for rolling in the order group requiring product thickness guarantee. However, this shows a case where the thickness is larger than the target rolling thickness of the order group for which the guarantee of the minimum thickness is required. The representative product thickness in this case is also the product thickness of the order group for which a guarantee of the lower limit thickness is required, and the target thickness for rolling the steel sheet is determined based on the above representative product thickness. Become thicker. Therefore, there arises a problem that the material weight needs to be increased accordingly.

  In case 4, the representative product thickness of the order group for which the product thickness guarantee is required is thicker than the representative product thickness of the order group for which the lower limit thickness guarantee is required. However, it shows the rolling target thickness when it is thinner than the rolling target thickness of the order group that requires the lower limit thickness guarantee. Although this case 4 cannot normally occur, it may possibly occur in an order where the lower limit tolerance of the lower limit thickness guarantee is severe. In this case, the representative product thickness is the product thickness of the order group for which product thickness guarantee is required, and the target thickness for rolling the steel sheet is determined based on the representative product thickness. Since it becomes thinner than the rolling target thickness, there is a risk that the tolerance lower limit thickness will be exceeded in products with a strict guarantee of the lower limit value.

  Therefore, in the present invention, a plurality of products that are cut from one thick plate have a product group that guarantees that the minimum thickness of the actual plate thickness is equal to or greater than the tolerance lower limit thickness of the product thickness, and in addition to the above results When configured with a product group that guarantees that the average thickness of the plate thickness is equal to or greater than the product thickness, a product group that guarantees that the minimum thickness of the actual thickness is equal to or greater than the tolerance lower limit thickness of the product thickness, In addition to the above, from the representative product thickness and representative tolerance lower limit thickness of each product group that guarantees that the average thickness of the actual sheet thickness is equal to or greater than the product thickness, the target thickness of each group is determined, and the thicker of them Has been adopted to adopt a method of setting the target thickness for rolling in the rolling instruction for the above-mentioned thick plate.

FIG. 4 shows a method for determining the thickness of a rolling target according to the present invention when a product collected from one thick plate is composed of an order group requiring “lower limit thickness guarantee” and an order group requiring “product thickness guarantee”. It explains the problem. As in FIG. 3, FIG. 4 shows the case where the number of orders in each order group is 1 for the sake of simplicity. The conditions for cases 1 to 4 were the same as in FIG.
As shown in FIG. 4, according to the method for determining the rolling target thickness of the present invention, it can be seen that an appropriate rolling target thickness can be set in any case.

  Contrast between products that require lower limit guarantees and those that use the method of the present invention in determining the thickness of steel sheets to be rolled when a product requiring product thickness guarantees is taken from a single plate. I will explain. In addition, the product thickness (nominal thickness) of the product used in the above description is 15.0 mm or 15.5 mm, and the thickness tolerance in the above product is the product thickness ± 0.3 mm, and the rolling of the group guaranteeing the tolerance lower limit thickness The additional thickness α for the lower limit thickness used for calculating the target thickness was 0.3 mm, and the additional thickness β for the product thickness used for calculating the rolling target thickness of the group guaranteeing the product thickness was 0.2 mm.

Table 1 shows the rolling of the above-mentioned plate when the product thickness guaranteed product A with a thickness of 15.0 mm and the product thickness guaranteed product B with a product thickness of 15.5 mm are taken from a single plate. It shows the result of obtaining the target thickness.
In this case, in the conventional method, the product thickness of B for which product thickness guarantee is required is the representative product thickness. Therefore, the value obtained by adding the additional thickness β (+0.2 mm) to the product thickness is the target thickness to be given to the rolling order. (15.7 mm).
On the other hand, in the method of the present invention, since the thicker one of the provisional rolling target thicknesses obtained by the respective groups of the lower limit thickness guarantee and the product thickness guarantee is set as the rolling target thickness, the target thickness given to the rolling order is 15.7 mm. The same result is obtained by the conventional method and the method of the present invention. The example in Table 1 corresponds to case 1 shown in FIGS.

Next, Table 2 shows a case where a product C requiring a product thickness guarantee of 15.5 mm and a product D requiring a product thickness guarantee of 15.0 mm are cut from one thick plate. The results of determining the thickness of the thick plate to be rolled are shown below.
In this case, in the conventional method, the product thickness of C for which product thickness guarantee is required is the representative product thickness. Therefore, the value obtained by adding the additional thickness β (+0.2 mm) to the product thickness is the target thickness to be given to the rolling command. (15.7 mm).
On the other hand, in the method of the present invention, since the thicker one of the provisional rolling target thicknesses obtained by the respective groups for the lower limit thickness guarantee and the product thickness guarantee is set as the rolling target thickness, the target rolling thickness given to the rolling order is 15.5 mm. Thus, a difference of 0.2 mm is generated as compared with the conventional method. That is, the method of the present invention can be rolled thinner by 0.2 mm, and the material (slab) weight can be reduced accordingly. The example in Table 2 corresponds to Case 2 shown in FIGS.

Next, Table 3 shows a case where a product E requiring a lower limit thickness guarantee of a product thickness of 15.5 mm and a product F requiring a product thickness guarantee of a product thickness of 15.0 mm are taken from one thick plate. The results of determining the thickness of the thick plate to be rolled are shown below.
In this case, in the conventional method, the product thickness of E for which product thickness guarantee is required is the representative product thickness, and therefore, the value obtained by adding the additional thickness β (+0.2 mm) to the product thickness is the target thickness to be given to the rolling command. (15.7 mm).
On the other hand, in the method of the present invention, among the provisional rolling target thicknesses obtained by the respective groups of the lower limit thickness guarantee and the product thickness guarantee, the thicker one is set as the rolling target thickness, so that the rolling target thickness given to the rolling order is 15.2 mm. Thus, a difference of 0.5 mm is generated as compared with the conventional method. That is, the method of the present invention can be rolled thinner by 0.5 mm, and the material (slab) weight can be reduced accordingly. The example in Table 3 corresponds to Case 3 shown in FIGS.

Next, Table 4 shows a case where a product G requiring a minimum thickness guarantee of 15.0 mm and a product H requiring a product thickness guarantee of 15.0 mm are taken from one thick plate. The results of determining the thickness of the thick plate to be rolled are shown below.
In this case, in the conventional method, since the product thickness is the same, the representative product thickness is 15.0 mm. Therefore, the value obtained by adding the additional thickness β (+0.2 mm) to the product thickness is the target thickness to be given to the rolling command. (15.2 mm).
On the other hand, in the method of the present invention, among the provisional rolling target thicknesses determined by the respective groups of the lower limit thickness guarantee and the product thickness guarantee, the thicker one is set as the rolling target thickness, so the rolling target thickness given to the rolling command is 15.3 mm. Thus, a difference of 0.1 mm occurs compared to the conventional method. That is, the method of the present invention rolls to a thickness of 0.1 mm, and the lower limit can be suppressed. The example in Table 3 corresponds to case 4 shown in FIGS.

Claims (1)

Plurality of ordered product to blank layout from one plank, and product groups to ensure that the minimum thickness of the actual plate thickness is equal to or greater than the thickness tolerance lower limit product thickness, the average of the actual thickness in addition to the When the product group that guarantees that the thickness is equal to or greater than the product thickness, the product group that guarantees that the minimum thickness of the actual plate thickness is equal to or greater than the tolerance lower limit thickness of the product thickness, In addition to the minimum thickness being equal to or greater than the tolerance lower limit thickness of the product thickness, each product group guarantees that the average thickness of the actual sheet thickness is equal to or greater than the product thickness. A method for manufacturing a thick plate, characterized in that a thickness intended for provisional rolling is obtained, and a thicker one of the thicknesses is set as a thickness intended for rolling in the rolling instruction for the thick plate. Here, the representative product thickness and is the thickest product thickness within one product group, also, the above-mentioned representative tolerance lower limit thickness refers to the thickest lower tolerance thickness within one product group.

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