JP6003871B2 - Steel plate straightening method and straightening device - Google Patents

Description

  The present invention relates to a steel plate straightening method and a straightening device for correcting warpage in the width direction of a steel plate using a roller leveler.

  In recent years, the shape inspection standard of a steel plate has become stricter in response to the increasing demand of customers for the flatness of the steel plate. For this reason, in order to meet the demands of customers, the steel plate factory measures the flatness of the steel plate by shape inspection, and when the flatness of the steel plate does not meet the standard, the steel plate is shipped after correcting the steel plate. Yes. For poor shape of steel sheet, poor flatness such as ear wave (steel plate wave generated at the end in the width direction) and medium wave (steel plate wave generated at the center in the width direction), warp in the longitudinal direction (L warp), and There are various forms such as a warp in the width direction (C warp), and various correction methods have been proposed to correct these shape defects.

  As a method for straightening thick steel plates, there are methods such as roller leveler straightening, press straightening, and heat straightening. Among them, roller leveler straightening is often performed with a relatively short processing time. However, the roller leveler is composed of a plurality of roll groups arranged in a staggered manner in the vertical direction along the longitudinal direction of the steel sheet, and bending strain is applied only in the longitudinal direction of the steel sheet by repeatedly bending the steel sheet by the roll group. Give. For this reason, the roller leveler correction is effective for correcting the L warp, but is not effective for correcting the C warp. Against this background, Non-Patent Document 1 describes a technique for correcting C warpage by applying a three-point bending strain to a steel sheet.

(Co.) Japan Society for Technology of Plasticity, "Straightening-How to straighten plates, pipes, bars and wires", Corona Co., Ltd., January 20, 1992, p.91.

  The technology described in Non-Patent Document 1 calculates the optimal amount of bending according to the amount of warpage before correction in anticipation of elastic recovery that occurs during unloading after bending the steel plate, and imparts bending strain to the steel plate using a press straightener. Then correct the C warp. However, press straightening is a process of straightening a steel sheet by applying bending strains to portions that require straightening. For this reason, according to the technique described in Non-Patent Document 1, a large amount of processing time is required to correct C warpage, and high productivity cannot be ensured.

  The present invention has been made to solve the above-described problems, and provides a steel plate straightening method and a straightening device capable of correcting warpage in the width direction of a steel plate without requiring a lot of processing time. Objective.

  In order to solve the above-described problems and achieve the object, the steel sheet straightening method according to the present invention includes a plurality of rolls arranged in a staggered manner in the vertical direction along the length direction of the steel sheet, and the width of the rolls. A roll crowning device capable of adjusting the amount of deflection in the direction, and a method of straightening the steel plate using a roller leveler, wherein the deflection in the width direction of the steel plate after correction is minimized. Calculating the amount as an appropriate amount of deflection and including the step of applying a bending strain in the width direction of the steel sheet by controlling the roll crowning device so as to apply the calculated amount of appropriate deflection to the roll. .

The straightening method for a steel sheet according to the present invention is the above-described invention, wherein the thickness t of the steel sheet, the yield stress σ _{e of the} steel sheet, the plastic deformation rate η in the second roll from the entrance side of the roller leveler, and 2 from the exit side of the roller leveler. An appropriate deflection amount Cr is calculated by using a function f shown in the following formula (1) using the reduction amount Δh in the second roll as a variable.

  In order to solve the above-described problems and achieve the object, a steel sheet straightening device according to the present invention includes a plurality of rolls arranged in a staggered manner in the vertical direction along the length direction of the steel sheet, and the width of the rolls. A roll crowning device capable of adjusting the amount of deflection in the direction, and the amount of deflection that minimizes the amount of warpage in the width direction of the steel sheet after correction is calculated as an appropriate amount of deflection, and the calculated amount of deflection is given to the roll. And a roll crowning control unit that applies a bending strain in the width direction of the steel sheet by controlling the roll crowning device.

  According to the steel sheet straightening method and straightening apparatus according to the present invention, the warpage in the width direction of the steel sheet can be straightened without requiring much processing time.

FIG. 1A is a front view showing a configuration of a roller leveler. FIG. 1B is a side view showing the configuration of the roller leveler. FIG. 2 is a schematic diagram for explaining deflection generated in the width direction of the upper and lower leveling rolls. FIG. 3 is a schematic diagram showing a state in which the steel plates are passed in a state where the upper and lower leveling rolls are bent in the width direction. FIG. 4 is a diagram showing a result of calculating the relationship between the amount of deflection of the upper and lower leveling rolls in the width direction of the steel sheet and the C warp height of the steel sheet after correction. FIG. 5 is a diagram showing the influence of the C warp height before correction on the C warp height after correction. FIG. 6 is a diagram illustrating an example of an appropriate deflection amount for each plate thickness and plastic deformation rate.

  In order to correct the C warpage of the steel sheet, it is necessary to apply a bending strain in the width direction of the steel sheet to reduce the residual stress in the width direction of the steel sheet. However, the conventional steel plate straightening method using a roller leveler has passed the steel plate in a state where the circumferential surface of the leveling roll is parallel to the width direction of the steel plate, and applied bending strain only in the longitudinal direction of the steel plate. , C was not effective in correcting warpage. For this reason, the steel sheet that could not correct the C warp by the roller leveler was sent to press correction or heat correction, and a lot of processing time was required to obtain the desired flatness.

  On the other hand, the inventors of the present invention, as a result of earnest research, as a result of correcting the steel sheet in a state where the leveling roll is bent in the width direction, by applying a bending strain in the width direction of the steel sheet, It has been found that even a roller leveler can effectively correct C warpage. The roller leveler used in the present invention has a configuration as shown in FIGS. 1A and 1B. 1A and 1B are a front view and a side view, respectively, showing the configuration of the roller leveler.

  As shown in FIGS. 1A and 1B, the roller leveler 1 used in the present invention has a plurality of upper and lower leveling rolls 2U and 2D arranged in a staggered manner in the vertical direction along the pass line through which the steel sheet S passes, The shape defect of the steel sheet S is corrected by repeatedly bending the upper and lower leveling rolls 2U and 2D. The upper and lower leveling rolls 2U and 2D function as rolls according to the present invention.

  The upper and lower leveling rolls 2U and 2D are supported by upper and lower backup rolls 3U and 3D, respectively, and the upper and lower backup rolls 3U and 3D are supported by integral upper and lower frames 4U and 4D. In addition, a plurality of wedges 5 are provided on the upper portion of the upper frame 4U along the width direction of the upper and lower leveling rolls 2U and 2D.

  The wedge 5 independently adjusts the amount of reduction in the width direction of the upper and lower leveling rolls 2U and 2D in order to adjust the deflection (see FIG. 2) generated in the width direction of the upper and lower leveling rolls 2U and 2D by the correction reaction force. By adjusting the amount of reduction in the width direction of the upper and lower leveling rolls 2U, 2D by the wedge 5, the steel sheet S is corrected in a state where the upper and lower leveling rolls 2U, 2D are bent in the width direction as shown in FIG. Can do. The wedge 5 functions as a roll crowning device according to the present invention.

  When straightening the steel sheet S using this roller leveler 1, the upper leveling roll 2U or the lower leveling roll 2D is tilted together with the frame, and the distance between the upper and lower leveling rolls 2U, 2D on the outgoing side is the upper and lower leveling rolls. The steel sheet S is passed through in a state narrower than the distance between 2U and 2D. The amount of reduction by the upper and lower leveling rolls 2U and 2D on the entry side and the exit side can be set individually by the entry and exit hydraulic cylinders 6 attached to the upper part of the roller leveler 1.

  FIG. 4 shows the result of calculating the relationship between the amount of deflection of the upper and lower leveling rolls in the width direction of the steel sheet and the C warp height of the steel sheet after correction. As calculation conditions, the thickness t of the steel sheet was 10, 20, 30 mm, the C warp height of the steel sheet before straightening was 100 mm per 4000 mm width, and the plastic deformation rate η was 80%.

  Here, the plastic deformation rate η is the ratio of the plastic deformation region in the plate thickness direction of the steel plate when bending is applied by the second leveling roll (leveling roll # 2 shown in FIG. 1B) from the entry side of the steel plate S. Yes, it is an index that is generally used as an index that represents the magnitude of bending at the roller leveler.

  The model used in this calculation is a slit model in which the plate thickness direction and the plate width direction are divided into elements, and analytically solves the repeated bending deformation behavior in each element. In this calculation, the residual stress in each element after correction is calculated, and the calculated residual stress is converted into a warp height.

  As shown in FIG. 4, according to this calculation, the upper and lower leveling rolls are deflected in the width direction in any condition as compared with the conventional correction method in which the roll deflection amount in the width direction is 0.0 mm. The C warp height of the steel plate after correction is reduced. It was also found that there is an optimum value for the amount of roll deflection in the width direction in which the C warp height after correction becomes zero.

  On the other hand, FIG. 5 is a diagram showing the influence of the C warp height before correction on the C warp height after correction. As shown in FIG. 5, the C warp height after correction was almost the same under both conditions of the C warp height before correction of 100 mm and 150 mm. From this, it was found that the influence of the C warp height before correction can be ignored. Based on these results, the steel sheet straightening method of the present invention straightens the steel sheet according to the following flow.

First, as shown in FIG. 6, the roll deflection amount in the width direction in which the C warp height after correction for each plate thickness t and plastic deformation rate η is zero is calculated as an appropriate deflection amount. Specifically, the thickness t of the steel sheet, the yield stress σ _{e of the} steel sheet, the plastic deformation rate η on the second leveling roll (leveling roll # 2 shown in FIG. 1B) from the entrance side of the roller leveler, and the exit side of the roller leveler The appropriate deflection amount Cr is calculated using the function f shown in the following formula (2) using the reduction amount Δh in the second leveling roll (leveling roll # 8 shown in FIG. 1B) as a variable. In actual operation, an appropriate deflection amount may be used as output data in accordance with the thickness t and the plastic deformation rate η from the data shown in FIG. Then, the wedge 5 is controlled so that the deflection amount in the width direction of the upper and lower leveling rolls 2U and 2D becomes an appropriate deflection amount. By correcting the steel sheet in this setting state, the C warpage of the steel sheet can be corrected without requiring much processing time.

  The steel sheet having C warpage was actually corrected by applying the present invention and the conventional correction method, and then the C warp height of the steel sheet corrected by each correction method was measured. The plate thickness of the steel plate was 20 mm, the plate width of the steel plate was 4000 mm, the yield strength of the steel plate was 400 MPa, and the C warp height before correction was 100 mm per 4000 mm width. The roller leveler had a maximum allowable load of 4200 tons with 5 lower and 4 upper leveling rolls (diameter 280 mm × body length 4850 mm), and the steel sheet was straightened with a plastic deformation rate η of 70% and 80%. Moreover, the C warp height after correction was measured on a surface plate. In addition, the shape inspection reference | standard of C curvature height in this material is 10 mm or less.

  The correction method of the present invention when the plastic deformation rate η is 70% was performed under the conditions (Example 1-1) in which the amount of deflection in the width direction of the upper and lower leveling rolls was 0.30 mm, which is an appropriate amount of deflection. Moreover, the conventional correction method was performed on the conditions (comparative example 1-1) which set the deflection amount to 0.00 mm, and the conditions (comparative example 1-2) which set the deflection amount to 0.50 mm. Similarly, in the case where the plastic deformation rate is 80%, the correction method of the present invention is performed under the conditions (Example 2-1) in which the deflection amount in the width direction of the upper and lower leveling rolls is 0.19 mm which is an appropriate deflection amount. went. Moreover, the conventional correction method was performed on the conditions (comparative example 2-1) which set the deflection amount to 0.00 mm, and the conditions (comparative example 2-2) which set the deflection amount to 0.50 mm.

  Table 1 below shows the plastic deformation rate η, the amount of deflection in the width direction of the upper and lower leveling rolls, and the C warp height after correction when the steel sheet is corrected by the present invention and the conventional correction method. As shown in Table 1, in the correction methods (Examples 1-1 and 2-1) according to the present invention in which the upper and lower leveling rolls have an appropriate amount of deflection, the C warp height satisfies the shape inspection standard. On the other hand, roll correction (Comparative Examples 1-1 and 2-1) in a flat state in the width direction, which is a conventional straightening method, and a case where the amount of deflection is larger than the appropriate amount of deflection (Comparative Example 1-2). In 2-2), the C warp height did not satisfy the shape inspection standard, and it was necessary to re-correct the steel sheet. From the above, it was confirmed that by applying the correction method of the present invention, the C warpage of the steel sheet can be corrected without requiring much processing time.

  As mentioned above, although the embodiment to which the invention made by the present inventors was applied has been described, the present invention is not limited by the description and the drawings constituting a part of the disclosure of the present invention according to this embodiment. What comprised each component suitably was also included in this invention. That is, other embodiments, examples, operational techniques, and the like made by those skilled in the art based on this embodiment are all included in the scope of the present invention.

1 Roller Leveler 2U Upper Leveling Roll 2D Lower Leveling Roll 3U Upper Backup Roll 3D Lower Backup Roll 4U Upper Frame 4D Lower Frame 5 Wedge 6 Hydraulic Cylinder S Steel Plate

Claims (2)

Warpage of a steel sheet using a roller leveler comprising a plurality of rolls arranged in a staggered manner in the vertical direction along the length direction of the steel sheet, and a roll crowning device capable of adjusting the amount of deflection in the width direction of the roll. A method of correcting a steel sheet for correcting
By calculating the deflection amount that minimizes the amount of warpage in the width direction of the steel plate after correction as an appropriate deflection amount, and by controlling the roll crowning device so as to give the calculated appropriate deflection amount to the roll, look including the step of imparting bending strain in the width direction,
The following variables are used: the thickness t of the steel sheet, the yield stress σ _{e of the} steel sheet , the plastic deformation rate η in the second roll from the entry side of the roller leveler, and the reduction amount Δh in the second roll from the exit side of the roller leveler. A method for correcting a steel sheet, wherein an appropriate deflection amount Cr is calculated using a function f shown in Formula (1) .

A plurality of rolls arranged in a staggered manner in the vertical direction along the length direction of the steel sheet;
A roll crowning device capable of adjusting the amount of deflection in the width direction of the roll;
By calculating the deflection amount that minimizes the amount of warpage in the width direction of the steel plate after correction as an appropriate deflection amount, and by controlling the roll crowning device so as to give the calculated appropriate deflection amount to the roll, A roll crowning control unit that applies bending strain in the width direction, and
The roll crowning control unit includes a steel sheet thickness t, a steel sheet yield stress σ _e , a plastic deformation rate η in the second roll from the entry side of the roller leveler, and a reduction amount in the second roll from the exit side of the roller leveler. An apparatus for correcting a steel sheet, wherein an appropriate deflection amount Cr is calculated using a function f shown in the following formula (1) with Δh as a variable .

Images