JP2005125332A - Method for straightening wide thick plate product - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for efficiently straightening a thick plate product, which can produce a high quality wide thick plate product which has a good flatness and causes no wave nor bend when cut into a predetermined size. <P>SOLUTION: The method is applied for straightening of a wide thick plate product being relatively thin among thick plates and having 5-10 mm thickness and 2.5 m or more width. A plate rolling mill has a structure to support working rolls with divided back-up rolls axially dividing a roller assembly into at least three divisions, on either of vertical sides. The plate rolling mill also has a load detection device, a roll-down structure, and a roll-down position detection device, divided independently for each divided back-up roll. When the product is straightened in an elongation rate between 0.05% and 1.20%, it is rolled in an elongation rate to obtain a desired flatness on the basis of a table of the preset elongation rate, flatness or the like. When the flatness of the product exceeds an allowance of the desired flatness, it is finish-straightened with a roller leveler. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention is a method for correcting a thin wide-width thick plate material, in particular, a thin wide-width thick plate material having a 0.2% proof stress of less than 600 MPa, a thickness of 5 mm or more and less than 10 mm, and a plate width of 2.5 m or more. In such a case, the present invention relates to a correction method capable of correcting the material to be corrected efficiently and stably to obtain a high-quality thick material.

In recent years, quality requirements for steel materials called thick steel plates with a thickness of 5 mm or more and a width of 2.5 m or more are becoming stricter, and various rolling and straightening techniques have been developed to meet this requirement. In general, the above-described thick steel plate is a steel plate rolling facility, that is, a plate rolling mill, and the finished rolled plate is subjected to finishing processes such as shearing, heat treatment, shape correction, and painting through a cooling device and / or a cooling floor. The product is shipped to the factory.
When this thick steel plate is secondarily processed by a manufacturer, a product that has no undulation or bending when the product is cut to a predetermined dimension is desired, but against the undulation or bending when the product is cut to a predetermined dimension. Since there is no effective means for dealing with this problem, it has been dealt with by correcting with a leveler or a press in order to guarantee flatness at the time of product shipment.

On the other hand, recently, at least one of the upper and lower roll assemblies has a mechanism for supporting a work roll by a divided backup roll divided into three or more in the axial direction, and each of the divided backup rolls has a load detection device independently. A plate rolling machine provided with a reduction mechanism and a reduction position detection device has been developed and proposed (see, for example, Patent Document 1 and Patent Document 2). In this rolling mill, the load distribution is detected for each of the divided backup rolls, the load distribution between the rolled material and the work roll is estimated, and the plate shape is controlled based on the estimated load distribution. It is not necessary to measure and feed back the plate shape on the exit side, and therefore the plate shape can be directly controlled without time delay. According to this plate rolling machine, good plate quality, that is, good plate profile and flatness can be obtained. Hereinafter, in the present invention, such a plate rolling machine is referred to as an intelligent plate rolling machine.
For obtaining a thick steel plate that does not generate bending or undulation during secondary processing by applying a light reduction to the thick steel plate that has been finish-rolled using such an intelligent plate rolling machine, see, for example, Patent Document 3 It has already been proposed by the inventors.

In other words, this intelligent plate rolling machine is a load cell attached to a split backup roll, which is the plate shape during rolling of the rolled material and the load distribution between the rolled material and the work roll during rolling, which is closely related to the shape. Therefore, the distribution of the load detection value of the divided backup roll becomes smaller as the rolling load at the time of light rolling correction is smaller. That is, the shape detection sensitivity of the intelligent plate rolling machine becomes insensitive. For this reason, the one where the rolling load at the time of light reduction of an intelligent type plate rolling mill is higher is preferable. As described above, when the rolling load is increased, the above-described shape detection sensitivity is increased, high-precision shape control is possible, and the thinness is a product that has good flatness and has no undulation or bending when the product is cut into a predetermined dimension. A plate material can be manufactured stably. On the other hand, increasing the rolling load at the time of correction of the thin thick plate material increases the elongation and cannot secure the desired plate thickness of the product. In addition, there is a problem that the flatness is likely to deteriorate (appearance) even if the stress remaining on the thick plate material after correction is small as the dimension of the thick plate material as the material to be corrected is thin and wide.
For this reason, thin and wide thick plate materials are generally corrected using a roller leveler. However, since the ability to correct the shape per pass is small, a plurality of repeated corrections are required depending on the shape of the material to be corrected. Become. In addition, after a plurality of passes are repeatedly corrected to some extent with a roller leveler, there is a problem that the correction effect is lost, and therefore, if the shape of the material to be corrected is bad, it cannot be corrected sufficiently.
JP-A-5-48375 JP-A-5-69010 JP 2002-66603 A

  An object of the present invention is to solve the problems of the above-described conventional method for correcting a thin, wide, thick plate material. The present invention corrects a thick plate material efficiently, has good flatness, and has a predetermined size. The present invention provides a straightening method capable of obtaining a high-quality thin wide-width thick plate material that does not generate undulation or bending when cut.

The gist of the present invention for solving the above problems is as follows.
(1) In the correction of a thin wide plate having a plate thickness of 5 mm or more and 10 mm or less and a plate width of 2.5 m or more, at least one of the upper and lower sides is divided into three or more divided backup rolls in the axial direction. This is a plate rolling machine that has a supporting mechanism and is provided with a load detection device, a reduction mechanism, and a reduction position detection device independently for each divided backup roll. When straightening at less than%, hold the relationship between steel type, plate thickness, elongation rate and flatness in advance as a table by experiment, and roll the thin wide plate with the elongation rate to obtain the desired flatness A method for straightening thin, wide, thick board materials.
(2) In the correction method according to claim 1, when the flatness of the corrected thin wide-thick plate material exceeds the desired flatness tolerance, the thin thickness is characterized by finishing correction in one pass with a roller leveler. Straightening method for plate materials.

  According to this invention, a thin and wide plate having a 0.2% proof stress of 600 MPa or less, a plate thickness of 5 mm or more and less than 10 mm, and a plate width of 2.5 m or more, which has not been sufficiently corrected conventionally. Since it can correct so that favorable flatness may be obtained, it became possible to supply a high quality thick board material stably.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a configuration diagram showing an example of rolling equipment for carrying out the present invention, and FIG. 2 is a configuration example of an upper division backup roll in an intelligent type plate rolling mill. In this example, the intelligent plate rolling machine is a vertically symmetrical 6-high rolling mill, and upper and lower inner housings 4, 4 ′ are supported in the mill housing 5 so as to be movable up and down. The upper work roll 1 is supported by the upper inner housing 4 through the upper work roll chock 3 so as to be displaceable in the vertical and horizontal directions. The lower work roll 1 'is supported by the lower inner housing 4' via the lower work roll chock 3 'so as to be displaceable in the vertical direction. As shown in FIG. 2, an upper entry side divided backup roll 2 a made up of 8 sets of divided backup rolls and an upper output side divided backup roll 2 b made up of 9 sets of divided backup rolls are independently mounted in the upper inner housing 4. It has been. Although not shown, the upper / outside divided backup rolls 2a and 2b independently have a reduction device, a load detection device, and a reduction position detection device.

  On the other hand, as with the upper divided backup roll, the lower input side divided backup roll 2a ′ composed of 8 sets of divided backup rolls and the lower outgoing side divided backup roll 2b ′ composed of 9 sets of divided backup rolls are respectively provided in the lower inner housing 4 It is attached independently in ′. Although not shown, the lower divided / outside divided backup rolls 2a ′ and 2b ′ are also independently provided with a lowering device, a load detecting device and a lowering position detecting device. It is the same.

    The upper inner housing 4 is moved up and down by the pass line adjusting device 6 to adjust the pass position of the material S to be corrected. A lowering force is applied to the lower inner housing 4 ′ by a hydraulic pressure reducing device 7. The upper and lower work rolls 1, 1 'have the same roll diameter, and although not shown, a spindle is connected to these upper and lower work rolls to transmit torque during rolling. The upper and lower work rolls are rotated via the reduction gear. Although not shown, a work roll bending apparatus is provided between the upper and lower work rolls 1 and 1 '.

    Table rollers 8 and 9 for conveying materials are installed on the entry and exit sides of the intelligent plate rolling machine. A roller leveler 12 is installed on the downstream pass line of the intelligent plate rolling machine. In the example shown in the drawing, an example of a general roller leveler is shown, but it is needless to say that other types of roller levelers (such as different numbers of rolls or different rolling methods) may be used. In the roller leveler 12 in this example, an upper roll group 10 and a lower roll group 11 are arranged in a housing, and each of the upper and lower rolls is arranged in a staggered manner. The material to be corrected passes through these upper and lower roll groups while repeatedly undergoing bending deformation, and correction is performed. Table rollers 13 and 14 for conveying materials are installed on the entrance and exit sides of the roller leveler 12.

An experiment was conducted using the above-described straightening machine. Thick plates used for straightening are those with a thickness of 5 to 20 mm, a width of 1.5 to 5 m, and a 0.2% proof stress of the material to be straightened from 300 to 600 MPa. Plate flatness before correction (per 1 m length) The average wave height (unit: mm / m) was 0.5 to 10 mm. This material was first corrected with an elongation of 0.05% to 1.20% in one pass using an intelligent plate rolling machine. A specific method of automatic shape control at the time of correction was performed by the method disclosed in Japanese Patent Laid-Open No. 8-267115, which has already been disclosed by the present inventors.
That is, in this type of intelligent plate rolling machine, the desired plate shape is obtained from the load distribution of the work roll to obtain the desired plate shape, the plate thickness distribution on the exit side of the rolling mill, and the matching conditions of the displacement of each roll of the rolling mill. A desired plate shape is obtained by obtaining the displacement of each divided backup roll to be obtained and controlling the displacement of each divided backup roll based on the obtained value.

    Table 1 shows the relationship between plate width, plate thickness, proof stress, and plate flatness after correction with an intelligent plate rolling machine. In Table 1, (a) is the relationship between the plate width and thickness and the flatness after correction when the 0.2% proof stress of the material to be corrected is about 300 MPa, and (b) is a value of 0. The relation between the plate width and thickness when the 2% proof stress is about 450 MPa and the flatness after correction, (c) is the plate width and thickness when the 0.2% proof stress of the material to be corrected is about 600 MPa. And the flatness after correction. In Table 1, the symbol ○ indicates that the flatness after correction is within 0.05 mm to 0.4% within 1 mm / m, and the symbol Δ indicates that the flatness after correction is 0.4%. In the case of over 1 mm / m, the plate flatness is within 1 mm / m when the elongation is up to 1.20%, and the symbol x is over 1 mm / m when the plate flatness after correction is 1.20%. Indicates something.

As disclosed in Patent Document 3, if the elongation is greater than 1.2%, the material deteriorates even if the flatness is improved. Even if the elongation rate is within 1.2%, the plate thickness decreases if the elongation rate is large. Therefore, it is necessary to increase the thickness reduction in advance during finish rolling. For this reason, the relationship between the steel type, the plate thickness, the elongation rate, and the flatness may be previously held as a table by experiment, and finish rolling may be performed as the above-described increase by the amount of elongation that provides the desired flatness.
As can be seen from Table 1 above, if the material to be straightened is a relatively thick plate material with a plate thickness of more than 10 mm and a plate width of less than 2.5 mm, it is corrected by an intelligent plate rolling mill. Accordingly, the flatness of the plate is within the allowable range of 1 mm / m (see the circles in Table 1). This is the same when the 0.2% proof stress of the material to be corrected exceeds 600 MPa. On the other hand, from Table 1, when correcting a thin wide plate having a 0.2% proof stress of the material to be corrected of 600 MPa or less and a plate thickness of 5 mm to 10 mm and a plate width of 2.5 m or more, When the flatness is obtained by improving the shape control accuracy by increasing the elongation and increasing the rolling load level in the straightening means where at least one of the upper and lower roll assemblies is an intelligent plate rolling machine (See Δ in Table 1) and even when corrected at an elongation of 1.20%, it can be seen that good flatness may not be obtained (plate flatness exceeds 1 mm / m). (See the crosses in Table 1).

  Next, an experiment was performed using the above-described roller leveler. Thick plate material used for roller leveler correction is plate thickness 5mm to 20mm, plate width 1.5m to 5m, and 0.2% proof stress of the correction material is 300MPa to 700MPa, flatness before correction (length 1m) The average wave height (unit: mm / m) was 0.5 to 10 mm. Table 2 shows the relationship between the plate width, thickness, and plate flatness after correction with a roller leveler when the 0.2% proof stress is about 300 MPa. In Table 2, the symbol ○ indicates that the flatness after correction is within 1 mm / m for one pass of the roller leveler, and symbol △ indicates that the flatness after correction is within 1 mm / m within 5 passes of the roller leveler and within one pass. X indicates that the plate flatness is more than 1 mm / m within 5 passes of the roller leveler.

  From Table 2, it was found that it was impossible to correct even a roller leveler alone with a thin wide plate material, and in particular, it was difficult to obtain a desired flatness even with a roller leveler 5 passes on the thin side. In view of productivity, the number of repetitions by the roller leveler is meaningless unless it is within 5 passes, and among these, 1-pass finishing is most preferable.

  Furthermore, an experiment was conducted in which correction using an intelligent plate rolling machine and correction using a roller leveler were combined. The target thick plate materials are those having a plate thickness of 4 mm to 20 mm, a plate width of 1.5 m to 5 m, and a 0.2% proof stress of the material to be corrected from 300 MPa to 600 MPa, and the flatness before correction (per 1 m length) The average wave height (unit: mm / m) was 0.5 to 10 mm. The material was first corrected with an elongation of 0.3% in one pass using an intelligent plate rolling machine, and then finished and corrected in one pass with a roller leveler. However, what was corrected by the roller leveler was limited to those having a flatness of more than 1 mm / m after correction by an intelligent plate rolling machine. Table 3 shows the results of correction.

In Table 3, (a) is the relationship between the plate width and thickness when the 0.2% proof stress of the material to be corrected is about 300 MPa and the plate flatness after correction according to the present invention, and (b) is the material to be corrected. Is the relationship between the plate width and thickness when the 0.2% proof stress is about 450 MPa and the flatness after correction according to the present invention, and (c) is when the 0.2% proof stress of the material to be corrected is about 600 MPa. The plate width and thickness of the plate and the flatness after correction according to the present invention. In Table 3, the symbol □ indicates that the flatness after correction of only the intelligent plate rolling machine is within 1 mm / m at an elongation of 0.3%, and the symbol ○ indicates that the flatness after correction of only the intelligent plate rolling machine. However, when the elongation rate is 0.3%, it is more than 1 mm / m, but the plate flatness is 1 mm / m or less in one pass correction by the roller leveler.
As described above, the present invention can efficiently produce a thin, wide and thick plate material that could not be corrected sufficiently only by correction using an intelligent plate rolling machine.
From the above, it has been clarified that the elongation can be corrected by increasing the elongation rate with the above-described intelligent plate rolling mill or by passing the roller leveler through one pass after rough correction.

The configuration shown in FIG. 1 was adopted as the rolling and straightening equipment, and the plate material was straightened under the following conditions and specifications.
・ Upper and lower work rolls: φ300mm × 6000mm
・ Upper and lower divided backup rolls: φ600mm x 250mm (24 divisions)
・ Roller leveler: Staggered arrangement of 4 upper rolls and 5 lower rolls (both φ250mm x 6000mm) (1 pass correction)
・ Rolling speed: 200m / min
-Material to be corrected: Steel type Low carbon steel, 0.2% proof stress of about 300 MPa, plate thickness 5 mm, 8 mm, 10 mm, plate width 2.5 m, 3.0 m, 3.5 m, 4.0 m, 5 .15 meters total divided into 20 meters (20 sheets per level)
As a result of straightening under the above conditions, the flat plate of the material to be straightened after rough correction at an elongation of 0.3% with an intelligent rolling mill in the first step and after one pass of final correction with a roller leveler in the second step All the degrees were less than 1 mm / m of flatness, and the average value of 20 sheets at one level was as shown in Table 4 below, and good flatness was obtained.

It is a lineblock diagram showing an example of rolling equipment for carrying out this invention. It is a top view which shows the example of a division | segmentation of the upper division | segmentation backup roll in the intelligent type plate rolling machine arrange | positioned in FIG.

Explanation of symbols

1, 1 ′: Upper and lower work rolls 2, 2a, 2b: Upper / lower side divided backup rolls 2a ′, 2b ′: Lower / outer side divided backup rolls 3, 3 ′: Upper / lower work roll chock 4, 4 ': Upper and lower inner housings 5: Mill housing group 6: Pass line adjusting device 7: Hydraulic pressure reducing device 8: Ingress table roller 9: Outlet table roller 10: Roller leveler upper and lower roll group 11: Roller leveler inner lower Roll group 12: Roller leveler 13, 14: Roller leveler entry / exit table roller S: Material to be corrected

Claims (2)

  A mechanism for supporting a work roll by a divided backup roll divided into three or more in the axial direction at least in any one of the upper and lower sides in correcting a thin wide plate having a thickness of 5 mm to 10 mm and a width of 2.5 m or more. Each of the divided backup rolls is provided with a load detection device, a reduction mechanism, and a reduction position detection device independently. When straightening, the relationship between the steel type, the plate thickness, the elongation rate and the flatness is previously held as a table by experiments, and the thin wide plate material is rolled at an elongation rate that provides the desired flatness. To correct thin, wide and thick plates.   The straightening method according to claim 1, wherein when the flatness of the corrected thin wide plate exceeds a desired flatness tolerance, the finishing correction is performed in one pass with a roller leveler. Method.

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