KR101736598B1

KR101736598B1 - Method for correcting of metal plate

Info

Publication number: KR101736598B1
Application number: KR1020150139681A
Authority: KR
Inventors: 정영진; 최억수; 김보성
Original assignee: 주식회사 포스코
Priority date: 2015-10-05
Filing date: 2015-10-05
Publication date: 2017-05-30
Also published as: KR20170040834A

Abstract

According to the present invention, there is provided a sheet material correcting method comprising: a sheet material deforming step of deforming a width direction non-flattened sheet material into a longitudinally non-flattened sheet material to planarize the sheet in the width direction; And a plate material planarizing step of longitudinally planarizing the longitudinally unperforated plate material.

Description

[0001] METHOD FOR CORRECTION OF METAL PLATE [0002]

The present invention relates to a sheet material correcting method, and more particularly, to a sheet material correcting method for eliminating a flatness defect of a sheet material.

High-temperature materials (slabs) produced by the continuous casting process and passed through a heating furnace are subjected to a rolling step such as a roughing and finishing mill to produce a predetermined thickness of the rear plate.

1, the material 1 produced by the continuous casting process is heated to the target temperature according to the type of steel in the heating furnace 3, and the heated material 1a is heated by the extruder 4 The rolled material 1b is firstly calibrated through the preliminary calibrator 6 and then the calibrated material 1c is subjected to grain refinement or control of the transformational structure Cooled by an accelerator cooler (7).

Then, the cooled material 1d is flat-calibrated through the hot-roll type sheet material correcting device 8 composed of a plurality of rolls to improve the quality, and then cooled in the cooling stand 9 and the surface and the flatness It is finished by inspection and final product.

At this time, if flatness defect occurs on the test board, the flatness is finally corrected through the cold roll type sheet material correcting apparatus 10 composed of a plurality of rolls for the flatness correction.

As shown in FIG. 2, the hot / cold roll type sheet material aligning apparatuses 8 and 10 include a plurality of upper calibrating rolls 8T and 10T and a lower calibrating roll 8B The upper and lower calibrating rolls 8T and 10B are arranged asymmetrically relative to each other with respect to the longitudinal direction of the upper calibrating roll 8T and the lower calibrating rolls 8B and 10B. Referred to as the material 1d cooled in Fig. 1) is pressed down by a certain force and calibrated.

When the sheet material 2 is pulled into the hot / cold roll type sheet material correcting devices 8 and 10, the upper and lower portions of the sheet material 2 are alternately subjected to tension and compression due to repeated bending. Accordingly, wavy deformation occurs and the degree of such deformation is relaxed as it exits the hot / cold roll type sheet material correcting devices 8 and 10, whereby the residual stress inside the sheet material 2 is relieved and the sheet material 2 ) Becomes flat.

On the other hand, the sheet material 2 introduced into the above-described hot / cold roll type sheet material aligning device 8 (10) has shape defects due to non-uniform plastic deformation and uneven cooling during hot rolling and cooling. There are a L-curved plate member 10 and a C-curved plate member C as shown in Fig.

At this time, the L curvature is generated by a non-uniform thickness direction distribution of the residual stress in the longitudinal direction of the plate material, and the C curvature is caused by the non-uniform thickness direction distribution of the residual stress in the width direction of the plate material.

Here, the C curve is generally caused by the unevenness of the upper and lower temperatures during cooling. In order to correct the C curve, the residual stress in the width direction must be controlled. However, due to the characteristics of the hot / cold roll type sheet material correcting device, About three times more force is needed.

Thus, unlike the hot / cold roll type sheet material correcting device 8 (10) shown in FIG. 2, it is possible to increase the facility capability of the hot / cold roll type sheet material correcting device through facility investment, In particular, when the plate is a high-strength steel with a strength of about 30t to 40t, most C curves are corrected by a press-type plate correcting device. In contrast to the roll type, which takes about 3 minutes per plate, Since the sheet material correcting device takes about 40 to 60 minutes per sheet, there is a limit in that the productivity due to the correction is greatly reduced.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide a sheet material correcting method capable of effectively eliminating a flatness defect in a width direction of a sheet material.

According to an aspect of the present invention, there is provided a method of calibrating a sheet material, the method comprising: deforming a sheet in a widthwise non-flattened state into a longitudinally non-planarized sheet material; And a plate material planarizing step of longitudinally planarizing the longitudinally unperforated plate material.

Here, the step of deforming the plate material may be an L curvature-generating step of deforming the C-curved plate material in the widthwise direction into an L-curvature in the longitudinal direction to remove the C-curvature, And may be an L curvature removal step for flattening the plate by removing curvature.

At this time, the L curvature generation step and the L curvature removal step may be performed by adjusting the input pressure or the output pressure of the roll-type plate material calibrating device.

Specifically, in the L curvature-generating step, it is preferable that the firing rate of the inlet side pressure is 70% to 95%.

In addition, in the L curve generation step, it is preferable that the output pressure lowering amount is 0.01 mm to 10 mm.

Furthermore, it is preferable that the L curvature generation step is performed at one-pass calibration, and the L curvature removal step is performed at two-pass calibration.

The sheet material correcting method according to the present invention is a method for correcting a relatively difficult width direction residual stress control by modifying a width direction nonplanarized sheet material into a longitudinally unplaced sheet material to flatten it in the width direction and then correcting the longitudinal direction non- It is possible to effectively eliminate the flatness defect in the width direction of the plate material by calling with stress control.

1 is a schematic view showing a general thick plate process.
FIG. 2 is a view showing a sheet material correcting apparatus in the thick plate process of FIG. 1. FIG.
3 is a view showing a plate material having a poor flatness.
Fig. 4 is a diagram showing residual stresses associated with sheet material deformation. Fig.
5 is a view showing the firing region, the elastic region, and the firing rate definition of the plate material.
FIGS. 6 and 7 are views showing the C curvature of the plate material transformed into the L curvature in the sheet material correction method according to the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail. In the drawings, like reference numerals are used to refer to like elements throughout the drawings, even if they are shown on different drawings. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

FIG. 4 is a view showing the residual stress associated with the deformation of the sheet material, FIG. 5 is a view showing the definition of the sintering zone, the elastic zone and the sintering rate of the sheet material. FIGS. 6 and 7 are cross- C curves to L curves.

Referring to the drawings, the present invention includes a sheet material deforming step and a sheet material planarizing step.

Specifically, the step of deforming the plate is a step of deforming the widthwise non-flattened plate material into a longitudinally non-flattened plate material to planarize the width direction.

In addition, the plate material planarization step is a step of longitudinally planarizing the longitudinally non-perforated plate material.

An example of the plate material deforming step and the plate material flattening step will be described as follows.

As shown in FIG. 3, the plate material to be calibrated may be, for example, a plate material 20 in which the widthwise non-flattened plate material is C-curved, and a plate material 20 in which the longitudinally unperforated plate material is L- have.

Accordingly, the plate material deforming step may be performed as an L curvature generating step of deforming the C-curved plate material 20 in the width direction into the longitudinally curved L curvature to remove the C curvature.

In addition, the planarizing step may be performed as an L curvature removing step of flattening the plate by removing the L curvature from the L curved plate 10.

Before describing the plate material deforming step and the plate material flattening step in detail, the C-curved plate material 20 as the widthwise non-flattened plate material and the L-curved plate material 10 as the longitudinally non- The causes of the C-curvature and the L-curvature are as follows, referring to FIGS. 3 and 4. FIG.

First, the C-curved plate member 20 as the widthwise non-flattened plate member is caused by the thickness direction non-uniformity of the residual stress in the width direction of the plate member 2, as shown in Fig.

That is, the width-direction non-flattened plate material is generated because the residual stress in the width direction of the plate material 2 is not uniform along the thickness direction of the plate material 2 but becomes different from each other in a non-uniform state. Particularly, the C-curved plate member 20 is formed when the residual stress in the width direction of the plate member 2 is directed in the opposite direction from the upper and lower sides of the plate member 2 in the thickness direction of the plate member 2.

Further, the L curved plate 10 as the longitudinally non-flattened plate material is caused by the thickness direction non-uniformity of the residual stress in the longitudinal direction of the plate material 2, as shown in Fig.

That is, the longitudinally unperforated plate material is generated due to the fact that the residual stress in the longitudinal direction of the plate material 2 is not uniform along the thickness direction of the plate material 2 but becomes different from each other. Particularly, the L-curved plate member 10 is formed when the longitudinal residual stress of the plate member 2 is directed in the direction opposite to the upper and lower sides of the plate member 2 in the thickness direction of the plate member 2.

Herein, the sheet material deforming step and the sheet material deforming step will be described in detail with reference to FIG. 6 and FIG. 7, among the sheet material deforming step and the sheet material smoothing step.

Referring to the drawing, the plate material deforming step is performed as an L curve forming step of deforming the C-curved plate material 21 (22 of Fig. 6 (c) 22) into L-curved plate material 10 .

The L curvature generation step serves to remove the C curvature by deforming the C-curved plates 21 and 22 in the widthwise direction into the L curvature in the longitudinal direction.

In other words, by deforming the C-curved plates 21 and 22 into a longitudinally curved L curvature by making the longitudinal direction residual stress uneven in the thickness direction, the thickness direction non-uniformity state of the residual stress in the width direction is made uniform, The C curves can be removed from the C-curved plates 21 and 22 by planarizing the direction.

For example, if the upper convex C-curved plate 21 is calibrated, as shown in Figs. 6 (a) and 6 (b), the upper convex C- _{Generates a} longitudinal upper tensile stress (? _Ltt ) while passing between the calibration rolls (BR) and generates a longitudinal lower compressive stress (? _Lbc ). Thus, as shown in Figs. 6 (b) and 6 (c), the upper and lower compressive stresses σ _wtc are generated and the lower tensile stress σ _wbt is generated, whereby the upper convex C- (M _u ) rising on both sides with respect to the center in the width direction of the main body portion 21 is generated, it is finally planarized with reference to the width direction.

7A and 7B, when the lower convex C-curved plate member 22 is calibrated, the lower-side convex C-curved plate member 22 is subjected to the upper and lower calibration rolls TR and TR, roll (BR) to generate a longitudinal upper compressive stress (σ _ltc) while passing through the lower portion generates a longitudinal tensile stress (σ _lbt). Thus, as shown in Figs. 7 (b) and 7 (c), the upper tensile stress σ _{wtt in} the width direction is generated and the lower compressive stress σ _{wbc in} the width direction is generated, (M _d ) of the both side portions downward with respect to the center of the widthwise direction of the base portion 22 is generated.

The planarization step, which is performed next, may be performed as an L curvature removal step of flattening the plate by removing the L curvature in the L curved plate 10. [

That is, by deforming the L-curved plate material 10 deformed in the C-curved plate materials 21 and 22 by the plate material deforming step, the longitudinal direction flattening is performed through the L curvature removing step, The sheet material can be calibrated.

At this time, the L curvature removing step is not limited to the present invention, and it is needless to say that any method including an existing method can be utilized by pressing down the upper and lower calibrating rolls TR and BR.

Meanwhile, the L curvature generation step and the L curvature removal step may be performed by adjusting the input pressure or the output pressure of the roll-type plate material calibrating device. That is, the present invention can be achieved by a sheet material calibrating apparatus in which a plurality of upper and lower calibrating rolls are disposed as a roll type, not a simple press type.

It is preferable that in the L curvature generation step for removing the C curves at the time of calibration by such a roll type calibrating roll, the firing rate of the inlet side pressure is 70% to 95%. In the case where the amount of the applied pressure does not fall within the range of the firing rate, the L curvature of the plate material is not sufficiently formed, and the correction effect becomes poor. When the firing rate range is exceeded, the L curvature of the plate material is excessively large, , The calibration roll, the backup roll, the drive shaft, etc., may cause damage to the equipment.

As shown in FIG. 2, the input pressure P i can be represented by the vertical length of the sheet fed to the calibrating device, and further, the firing rate shown in FIG. 5. In this case, the firing rate refers to the percentage of the firing area occupied by the total length (t) of the thickness with reference to the thickness direction of the plate.

In addition, in the L curve generation step, it is preferable that the output pressure lowering amount is 0.01 mm to 10 mm. If the amount of the outgoing pressure does not fall within this range, the L curvature of the plate material is not sufficiently formed, and the correction effect becomes inferior. If it exceeds this range, the L curvature of the plate material becomes too large, , Backup rolls, drive shafts, etc., may damage the equipment.

As shown in FIG. 2, the outgoing pressure lowering amount Po means an upper and lower length as much as the plate material immediately before leaving the calibrating apparatus is depressed.

Furthermore, it is preferable that the L curvature generation step is performed during one-pass calibration, and the L curvature removal step is performed during two-pass calibration.

Specifically, since the L curvature generation step and the L curvature cancellation step can not be all performed at the time of one-pass calibration, they are performed at the time of one-time pass calibration so that the C-curved plate material is corrected by the two- . Of course, the calibration of the C-curved plate is not limited by the present invention, but may be accomplished by at least two passes of the calibration, preferably by reducing the calibration time by two passes of calibration, thereby increasing calibration productivity . It is needless to say that the input pressure and the output pressure of the calibrating roll for the calibration of the two pass passes can be appropriately adjusted according to the shape condition of the plate and the facility capability of the calibrating device.

As a result, the present invention can be achieved by modifying the widthwise non-flattened plate material into a longitudinally unplaced plate material to planarize it in the width direction and then calibrate the longitudinal unplasticisation to achieve relatively difficult width directional residual stress control with longitudinal residual stress control According to the telephone, it is possible to efficiently eliminate the flatness defect in the width direction of the plate material.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. It is to be understood that various changes and modifications may be made without departing from the scope of the appended claims.

10: L curved plate material 20, 21, 22: C Curved plate material
Pi: Lower pressure on the inlet side Po: Lower pressure on the outlet pressure
σ _ltt : longitudinal tensile stress σ _ltc : longitudinal compressive stress in the longitudinal direction
σ _lbt : longitudinal tensile stress σ _lbc : longitudinal compressive stress in the longitudinal direction
σ _wtt : upper tensile stress in the width direction σ _wtc : upper compressive stress in the width direction
σ _wbt : Width lower tensile stress σ _wbc : Width lower compressive stress
M _u , M _d : moment

Claims

Deforming the width direction non-flattened plate material into a longitudinally non-flattened plate material to planarize the width direction; And
A planarizing step of planarizing the longitudinally unperforated plate material in the longitudinal direction;
.

The method according to claim 1,
The step of deforming the plate material is an L curvature-generating step of deforming the C-curved plate material in the widthwise direction into an L-curvature in the longitudinal direction to remove the C-curvature,
Wherein the step of planarizing the sheet material is an L curvature removal step of flattening the sheet material by removing the L curvature from the L curved sheet material.

3. The method of claim 2,
Wherein the L curvature generating step and the L curvature removing step are performed by adjusting the amount of the input pressure or the amount of the output pressure of the roll-type plate material calibrating device.

The method of claim 3,
Wherein in the L curvature generation step, the input side pressure reduction amount is in the range of 70% to 95%.

The method of claim 3,
Wherein in the L curvature generation step, the amount of the downward pressure is 0.01 mm to 10 mm.

6. The method according to any one of claims 2 to 5,
Wherein the L curvature generation step is performed at one-pass calibration, and the L curvature removal step is performed at two-pass calibration.