JP2005021960A - Steel plate manufacturing method and manufacturing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method and a manufacturing apparatus of a flat bar with excellent dimensional accuracy using a universal mill and a horizontal mill, in particular, with little variation in sheet thickness in the width direction. is there.
In order to achieve the above object, the present invention provides a universal mill having a pair of horizontal rolls for a universal mill and a pair of vertical rolls, and a horizontal mill having a pair of horizontal rolls for a horizontal mill. In the method of manufacturing a steel sheet using the horizontal mill, the vertical roll of the universal mill and the horizontal roll for universal mill respectively perform rolling in the width direction and rolling in the thickness direction of the material to be rolled, and then the horizontal roll for horizontal mill There is provided a manufacturing method and a manufacturing apparatus for a steel sheet, characterized in that the rolling of the material to be rolled is performed in the thickness direction using the horizontal mill in which the shape of the pressed surface is an inverted crown shape.
[Selection] Figure 2

Description

  The present invention relates to a steel plate manufacturing method and manufacturing apparatus using a universal mill and a horizontal mill.

  Conventionally, when a steel sheet is hot-rolled using a universal mill widely used for hot rolling of H-shaped steel, the breakdown mill 1 (FIG. 8 (a)) and the universal mill 2 are processed by a process as shown in FIG. (FIG. 8 (b)) and the horizontal mill 3 (FIG. 8 (c)) are generally used, but in the conventional method, different product widths are particularly obtained by using the same horizontal roll of the universal mill. When manufacturing a steel plate, variation in the plate thickness occurred in the product width direction.

For example, in the rolling of flat steel and wide flat steel using a universal mill, the roll of the edger mill arranged on the outlet side is a free-size flat roll, so only the roll interval of the universal mill is changed (the roll is It is possible to roll several types of different widths and thicknesses, and these rolling methods tend to be frequently used recently. (See Patent Document 1)
However, in the above rolling method, when rolling flat steel or wide flat steel with greatly different dimensions such as width, avoid deterioration of the shape of the end face in the width direction of the flat bar (the angle between the surface of the flat bar and the end face). The horizontal roll of the universal mill has a predetermined width in relation to the vertical roll (with the gap between the roll body of the vertical roll and the roll end surface of the horizontal roll within a predetermined range). It is necessary to change to a roll with Therefore, the current situation is that a rapid response cannot be made when rolling a small lot and a multi-size flat steel.

  Therefore, in Patent Document 2, a method of manufacturing a flat steel is proposed in which a universal mill having a variable width horizontal roll and an edger mill having a variable width roll are used to adjust the width of each roll on the production line. Has been. In the invention, the rolled material for flat steel is reduced in the longitudinal direction by the horizontal roll of the universal mill, and the subsequent edger mill performs rolling to reduce only the uncompressed lower portion formed on the rolled material. The present invention relates to a flat steel rolling method and rolling equipment for realizing the method.

  However, in the methods disclosed in Patent Document 1 and Patent Document 2, a tensile force acts in the rolling direction at the center of the material to be rolled during rolling, so that the thickness is thinner than the actual opening of the horizontal roll. . On the other hand, since the extension in the rolling direction is larger at the other parts, particularly at both ends in the width direction, compared to the central part, a compressive force acts as a result in the rolling direction, and the horizontal roll outlet is thicker than the gap between the rolls. (Thickness is restored). Therefore, the thickness distribution in the width direction of the material to be rolled at the outlet of the horizontal roll mill gradually increases in the both end directions as compared with the center portion.

  From the above, it has not been possible to produce a flat bar with excellent dimensional accuracy and particularly with little variation in plate thickness by a conventional method using a universal mill.

Japanese Patent Laid-Open No. Sho 62-21402

JP-A-5-329503

  The present invention has been made in view of the above problems, and provides a method and an apparatus for manufacturing a flat steel with excellent dimensional accuracy using a universal mill and a horizontal mill, particularly with less variation in sheet thickness in the width direction. The main purpose is to do.

  In order to achieve the above object, the present invention provides a steel plate using a universal mill having a pair of horizontal rolls for a universal mill and a pair of vertical rolls, and a horizontal mill having a pair of horizontal rolls for a horizontal mill. In the manufacturing method, the vertical roll of the universal mill and the horizontal roll for the universal mill are respectively pressed in the width direction and the thickness direction of the material to be rolled, and then the pressed surface of the horizontal roll for the horizontal mill is reduced. There is provided a method for producing a steel sheet, characterized in that the rolling of the material to be rolled is performed using the horizontal mill having an inverted crown shape.

  The shape of the horizontal roll for the horizontal mill of the horizontal mill takes into account the restoration in the thickness direction at both ends in the width direction of the material to be rolled at the outlet of the horizontal roll for the horizontal mill. Dimensional accuracy after processing of the material to be rolled is improved by making the opening of the horizontal roll for the horizontal mill the above shape so that the opening of the horizontal roll for the horizontal mill is narrower at both ends than the center part. Can be made.

  Further, in the present invention, in the steel plate manufacturing apparatus having a universal mill having a pair of universal mill horizontal rolls and a pair of vertical rolls, and a horizontal mill having a pair of horizontal mill horizontal rolls, The horizontal roll for a horizontal mill of the horizontal mill provides a steel plate manufacturing apparatus characterized in that the shape of the pressed surface is an inverted crown shape. By using the manufacturing apparatus, it is possible to realize the manufacture of a steel plate with excellent dimensional accuracy.

  Furthermore, in the present invention, it is preferable that the universal mill and the horizontal mill are arranged close to each other. This is because repeated rolling by a universal mill and a horizontal mill becomes possible. By repeatedly passing the universal mill and the horizontal mill alternately, it becomes possible to further improve the dimensional accuracy of the product.

  According to the present invention, the bulging portion at both ends of the material to be rolled that occurred during width reduction rolling in the breakdown mill, and the unpressed lower portion near the both ends of the material to be rolled that occurs during the subsequent universal mill rolling are horizontally milled. When rolling down in the thickness direction with a horizontal roll for a horizontal mill, the horizontal roll for the horizontal mill can be a reverse crown-shaped roll so that the vicinity of both ends of the material to be rolled can be more strongly reduced than the center. become. Therefore, even if there is some restoration of thickness at both ends in the width direction of the material to be rolled at the horizontal roll outlet for the horizontal mill, the thickness in the width direction is larger than when a flat roll is used for the horizontal mill. It is possible to obtain a steel sheet having excellent dimensional accuracy with little variation in the above. This makes it possible for the manufacturer to improve the yield by improving the dimensional accuracy of the product, and for the consumer, the assembly accuracy is improved by using the steel sheet, and the workability is improved by reducing the rework work. There is an effect that becomes possible.

  The present invention relates to a steel plate manufacturing method and manufacturing apparatus using a universal mill and a horizontal mill. Hereinafter, these will be described in detail.

  In the present invention, the steel plate refers to a thick steel plate, a flat steel, and a wide flat steel having excellent flatness of the product end face. According to JISG0204, a thick steel plate is a hot rolled steel plate having a thickness of 3 mm or more, a flat steel is a steel bar having a rectangular cross section, and the product is rolled on all four sides. 5 mm or more and the width does not exceed 500 mm. Further, the wide flat steel refers to a finished plate product having a width exceeding 150 mm and a thickness generally exceeding 4 mm, which is always stretched, that is, not made into a coil. The end face is sharp and the wide flat steel is obtained by hot rolling all four faces (or rolling with a box-shaped caliber), or by shearing or flame cutting a wider plate.

A. Steel plate manufacturing method The steel plate manufacturing method of the present invention uses a universal mill having a pair of horizontal rolls for a universal mill and a pair of vertical rolls, and a horizontal mill having a pair of horizontal rolls for a horizontal mill. In the manufacturing method of the present invention, the vertical roll of the universal mill and the horizontal roll for the universal mill are respectively pressed in the width direction and the thickness direction of the material to be rolled, and then the pressed surface of the horizontal roll for the horizontal mill. The steel sheet is reduced in the thickness direction of the rolled material using the horizontal mill having a reverse crown shape.

  FIG. 1 is a diagram showing an example of the flow of a method for producing a steel sheet of the present invention, and FIG. 2 is a schematic process diagram illustrating each process of FIG. In the method for producing a steel sheet according to the present invention, a rough rolling step in which a raw material is a rough steel slab 4 using a breakdown mill 1, the rough steel slab 4 is disposed in proximity to the universal mill 2 and the universal mill 2. By repeated rolling with the horizontal mill 3, it can be roughly divided into two processes, that is, a finish rolling process for finishing a product. Each process will be described below.

1. Rough rolling process In the steel sheet manufacturing method of the present invention, first, the material is heated to 1200 to 1300 ° C. in a heating furnace, and the thickness direction is measured by a breakdown mill 1 having a double horizontal roll having a plurality of perforations already installed. Repeated rolling of reduction (thick reduction) and reduction in the width direction (width reduction) is performed while rotating 90 ° to obtain a rough steel slab 4 (see FIG. 2 (a)). At this time, a continuous casting slab, a block slab, or the like is preferably used as the material.

  In general, when the width of the material in the breakdown mill 1 is reduced, bulging portions 5 corresponding to the amount of reduction are generated at both ends in the width direction of the material.

2. Finishing rolling step In the method for producing a steel sheet of the present invention, the rough steel slab obtained by the rough rolling step is repeatedly rolled by a universal mill and a horizontal mill adjacent to the universal mill to finish the product. In the present invention, a shape having a uniform roll diameter in the body length direction is defined as a flat shape, and a roll having a flat shaped pressure surface is defined as a flat shape roll. Further, a shape having a larger diameter at both end portions than the center portion of the body portion is a reverse crown shape, and a roll having a reverse crown-shaped pressing surface is a reverse crown shape roll.

  As illustrated in FIG. 2B, the universal mill 2 used in the present invention includes a pair of horizontal rolls 6 for a universal mill having a body length narrower than the width of the material 4 to be rolled, and a pair of vertical rolls. The universal roll horizontal roll 6 and the vertical roll 7 are both flat rolls. In the reduction by the universal mill 2, the width center portion of the material to be rolled 8 is crushed in the thickness direction by the horizontal roll 6 for the universal mill, and the material to be rolled 8 is crushed in the width direction by the vertical roll 7. At this time, under the thickness reduction by the universal mill horizontal roll 6, both width ends of the material 8 to be rolled are not subjected to the reduction by the universal mill horizontal roll 6 and remain uncompressed.

  The length of the universal mill horizontal roll for the universal mill depends on the rolling conditions such as the width, thickness, material, rolling temperature, mill rigidity, rolling amount (rolling ratio) of the steel plate being rolled. It can be adjusted empirically or theoretically so that the thickness of the plate becomes uniform.

  The horizontal mill 3 is composed of a pair of horizontal rolls 9 for horizontal mills having a reverse crown-shaped pressing surface (see FIG. 2C). In the reduction by the horizontal roll 9 for the horizontal mill, the entire width of the material to be rolled 8 is reduced in the thickness direction.

  FIG. 3 shows an example of the reverse crown shape of the pressure surface of the horizontal roll 9 for the horizontal mill. As illustrated in FIG. 3A, the reverse crown-shaped roll of the present invention has a predetermined range at the center of the roll as a flat shape portion 10 and a predetermined range at both ends as an arc-shaped portion 11 having a radius of curvature R. Is applicable. In addition, the flat shape portion 10 as illustrated in FIG. 3B or the arc shape portion 11 as illustrated in FIG. 3C is not only a single arc but also two or more different radii. These arcs (radius of curvature R1, R2) may be combined.

  The reverse crown shape of the horizontal roll for the horizontal mill of the horizontal mill is based on the rolling conditions such as the width, thickness, material, rolling temperature, mill rigidity, rolling amount per roll (rolling rate), etc. It can be adjusted empirically or theoretically so that the product thickness is uniform.

  The reverse crown shape of the horizontal roll for horizontal mills of the present invention varies depending on the rolling conditions described above. For example, when manufacturing a steel plate having a width of 450 to 550 mm and a thickness of 25 to 35 mm, the roll diameter difference between the roll width center portion and the roll width direction position corresponding to the width end portion of the material to be rolled is 0. A reverse crown shape in the range of 4 to 2.0 mm is preferable.

  In addition, when it has a flat shape part and a single circular arc shape part as shown to Fig.3 (a), the circular arc radius R is computed from following Formula.

  Here, for example, in the case of a steel plate having a width of 450 to 550 mm and a thickness of about 25 to 35 mm, in the above formula, Δt = 0.4 to 1.2 mm and α = 0.6 to 0.9, so R = It can be in the range of 1300-5600 mm.

  In the present invention, as illustrated in FIGS. 4 and 5, another horizontal mill 12 with a flat roll can be arranged downstream of the horizontal mill 3 in FIG. 1. In this case, the horizontal roll of the horizontal mill 3 is a horizontal roll 9 for a horizontal mill having a reverse crown shape (FIG. 5C), and the horizontal roll of the horizontal mill 12 with a flat-shaped roll is a flat horizontal roll for a flat horizontal mill. 13 (FIG. 5D).

  In the manufacturing method using a horizontal mill and a horizontal mill with a flat shape roll, the rough steel slab obtained by the rough rolling process is repeatedly rolled by three mills: a universal mill, a horizontal mill, and a horizontal mill with a flat shape roll. A product can be obtained. Or you may roll using a horizontal mill with a flat-shaped roll as a final pass, after rolling a rough shaped steel slab repeatedly with two mills, a universal mill and a horizontal mill. Further, a horizontal mill with a flat roll can be used in combination with a horizontal mill in a rolling pass other than the final pass. Furthermore, repeated rolling can be performed by a combination of a universal mill and a horizontal mill with a flat roll.

  Furthermore, in addition to the above, in a method of manufacturing a steel sheet by alternately rolling a plurality of universal mills and a plurality of horizontal mills in tandem and performing continuous rolling, at least one of the plurality of horizontal mills By using the reverse crown-shaped roll for the horizontal roll of the horizontal mill, the same effects as in the other embodiments can be obtained.

B. Steel Plate Manufacturing Apparatus The steel plate manufacturing apparatus of the present invention includes a universal mill having a pair of universal mill horizontal rolls and a pair of vertical rolls, and a horizontal mill having a pair of horizontal mill horizontal rolls. In the steel plate manufacturing apparatus, the horizontal mill horizontal roll of the horizontal mill is a steel plate manufacturing apparatus characterized in that the shape of the pressed surface is an inverted crown shape.

  Since the universal mill and the horizontal mill used in the production apparatus of the present invention are the same as the above-mentioned “A. Method for producing a steel plate”, description thereof is omitted here.

  The production apparatus of the present invention uses the above-mentioned universal mill and a horizontal mill having an inverted crown-shaped roll in combination. In addition to that, a horizontal mill with a flat roll having a flat roll may be used. By using the two or three types of mills, and adjusting the opening and shape of each mill roll, the combination of mills, the order of mills, etc. according to the conditions of the steel sheet to be manufactured, the dimensional accuracy is excellent. Steel sheets can be manufactured.

  Moreover, in the manufacturing apparatus of this invention, it is preferable that the said universal mill and the said horizontal mill are arrange | positioned closely. This is because repeated rolling by a universal mill and a horizontal mill becomes possible by arranging them close to each other. By repeatedly passing the universal mill and the horizontal mill alternately, it becomes possible to further improve the dimensional accuracy of the product.

  The present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, and the present invention has any configuration that has substantially the same configuration as the technical idea described in the claims of the present invention and that exhibits the same effects. Are included in the technical scope.

  The following examples further illustrate the invention.

[Example]
Using the rolling line illustrated in FIGS. 1 and 2, a wide flat steel of width 500 mm × thickness 30 mm and SS400 standard was manufactured. A continuous cast slab having a width of 550 mm and a thickness of 250 mm was used as a raw material, and it was heated to 1250 ° C. and rolled.

  First, a rough steel slab having a width of 500 mm and a thickness of 100 mm was obtained after rolling for 10 or more passes by a breakdown mill. Subsequently, 11-pass reverse rolling was performed using a universal mill (horizontal roll barrel length for universal mill: 400 mm) and a horizontal mill (reverse crown shape horizontal roll barrel length for horizontal mill: 700 mm) to finish the product. At this time, as the shape of the horizontal roll for the horizontal mill, the shape illustrated in FIG. 3A having an arc radius of 4000 mm and a flat part length of 380 mm was used.

  The thickness distribution in the width direction of the wide flat steel manufactured in this example is shown by ● in FIG.

[Comparative example]
Using the rolling line illustrated in FIGS. 7 and 8, a wide flat steel of width 500 mm × thickness 30 mm and SS400 standard similar to the example was manufactured. At this time, manufacturing conditions other than the use of a horizontal mill with a flat-shaped roll as a horizontal mill, that is, slab dimensions, slab heating conditions, roll hole type and rolling pass schedule of breakdown mill, universal mill and horizontal mill pass The schedule was performed in the same manner as in the example.

  The thickness distribution in the width direction of the wide flat steel manufactured in this comparative example is shown by ○ marks in FIG.

  From FIG. 6, the wide flat bar manufactured in the example has a thickness distribution with little variation in the width direction, whereas the wide flat bar manufactured in the comparative example has an allowable thickness at both ends. It can be seen that the difference (tolerance ± 0.7 mm specified in JIS 3193) is deviated.

It is a schematic process drawing which shows an example of the flow of the manufacturing method of the steel plate of this invention. It is a schematic sectional drawing which shows the example of each process of FIG. It is a schematic sectional drawing which shows the example of the shape of the reverse crown shape roll of this invention. It is a schematic process drawing which shows the other example of the flow of the manufacturing method of the steel plate of this invention. It is a schematic sectional drawing which shows the example of each process of FIG. It is a figure which shows thickness distribution of the width direction of the wide flat bar manufactured in the Example and the comparative example. It is a schematic process drawing which shows an example of the flow of the manufacturing method of the conventional steel plate. It is a schematic sectional drawing which shows the example of each process of FIG.

Explanation of symbols

2 ... Universal mill 3 ... Horizontal mill 6 ... Horizontal roll for universal mill 7 ... Vertical roll 8 ... Roll material 9 ... Horizontal roll for horizontal mill 12 ... Horizontal mill with flat roll

Claims (3)

In the manufacturing method of the steel plate using the universal mill which has a pair of horizontal roll for universal mills, and a pair of vertical rolls, and a horizontal mill which has a pair of horizontal rolls for horizontal mills, Using the horizontal mill, a horizontal roll for the universal mill performs a reduction in the width direction and a reduction in the thickness direction of the material to be rolled, and then uses the horizontal mill in which the shape of the pressed surface of the horizontal roll for the horizontal mill is an inverted crown shape. A method of manufacturing a steel sheet, wherein the rolling of the material to be rolled is performed in the thickness direction. In the steel plate manufacturing apparatus having a universal mill having a pair of horizontal rolls for universal mill and a pair of vertical rolls, and a horizontal mill having a pair of horizontal rolls for horizontal mill, the horizontal mill of the horizontal mill The horizontal roll for use is a steel plate manufacturing apparatus characterized in that the shape of the pressed surface is an inverted crown shape. The steel sheet manufacturing apparatus according to claim 2, wherein the universal mill and the horizontal mill are arranged close to each other.

Images