JP2001316755A - Steel sheet, method for producing steel sheet and device for producing steel sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To restrain the nonuniformity generated during the production of a steel sheet such as residual stress within a specified range so that the amount of a distortion is kept within a constant range when the steel sheet is subjected to groove cutting. SOLUTION: The temperature distribution in the surface of a steel sheet 8 subjected to hot straightening by a hot straightening device 5 is measured by a thermometer 7, the distribution of residual stress or the like is calculated from the temperature distribution in the steel sheet 8 by a deformation estimating computer 18 or the like, and a prescribed parameter χ is calculated from the distribution of residual stress or the like. Further, the allowable value (the upper limit value χcmax and the lower limit value χcmin) of the parameter χpreviously set, e.g. in accordance with the allowable error of a root shape at the time of groove cutting by a demander and the parameter χ are compared, and, in the case the parameter χ does not lie within the allowable range, straightening treatment is performed by using a straightening device 10, a heat treating furnace 9 or the like to reduce its residual stress or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steel sheet which is controlled such that the variation in the amount of deformation at the time of groove cutting performed prior to welding of the steel sheet is within a certain range.

[0002]

2. Description of the Related Art In a general method of manufacturing a steel sheet, for example, a slab is heated to about 1000 to 1200 ° C., and hot rolling (rough rolling and finish rolling) is performed until the slab reaches a predetermined size.
Furthermore, TMCP (Thermo-Mechanical Control Procedures)
s) In the case of a steel sheet, after performing accelerated cooling or direct quenching, the steel sheet is flattened by hot straightening, and cut to a predetermined size by gas cutting, plasma cutting, laser cutting or shear cutting.

[0003] Non-uniform residual stress is generated in the steel sheet due to variations in various manufacturing conditions in each of the above steps. For example, cooling during water cooling due to uneven temperature during heating (uneven heating), poor flatness during rolling (waves and warpage), plate thickness deviation, and uneven scale properties (scale components and thickness) of the surface Unevenness, uneven cooling during accelerated cooling or descaling (especially around the steel plate), deviation of zero point and roll deflection during hot straightening, uneven cooling during air cooling, stress and structural changes due to thermal effects during thermal cutting. Hardening, cutting distortion when shearing, zero point deviation and roll deflection during cold straightening, differences in surface properties during heat treatment
(Presence or absence of care or shot blast) is the cause.

Conventionally, characteristics such as residual strain, residual stress, displacement or parameters calculated from these according to processing information in a consumer, for example, welding conditions, welding method, processing shape and allowable value of processing accuracy, etc. There was no steel sheet controlled.

[0005]

Prior to welding, when a conventional steel sheet having the above-mentioned residual stress is groove-cut, the steel sheet bends laterally due to release of heat at the time of cutting and the stress caused by cutting, and out-of-plane deformation, In some cases, deformation in the width direction, deformation in the longitudinal direction, groove dimension failure, and the like may occur. When these shape defects occur, in butt welding after groove cutting, there is a possibility that poor penetration and defective product shape may occur,
There has been a problem that it is necessary to perform rework after welding, or the product must be disposed of, which causes a reduction in productivity and yield.

Further, in order to avoid rework after welding and discard of the product, after the groove is cut, the cut surface of the groove is corrected by machining using a grinder, a milling machine, or the like. Had a problem that it was large.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and a steel sheet whose characteristics are controlled so that the variation in the amount of deformation when cutting a groove is within a certain range. An object of the present invention is to provide a steel sheet manufacturing method and a steel sheet manufacturing apparatus for manufacturing a steel sheet.

[0008]

Means for Solving the Problems In order to achieve the above-mentioned object, the steel sheet of the present invention is produced by controlling the manufacturing conditions of the steel sheet so that the variation in the amount of deformation when the steel sheet is grooved is within a certain range. characteristic parameter that represents the unevenness chi is, the lower limit of the chi _c ^min tolerance, as an upper limit chi _c ^max tolerance, that is controlled so as to satisfy the ^{_{χ c min ≦ χ ≦ χ c}} max to And

Preferably, the parameter χ is determined from the residual stress of the steel sheet.

Further, assuming that the maximum value of the stress on the plate surface is σ _max , the minimum value of the stress on the plate surface is σ _min , and the correction coefficients relating to the width and length of the product are W ′ and L ′, respectively, the parameter χ is χ It is preferable that ₁ = (σ _max −σ _min ) · W ′ · L ′.

Further, the parameter χ is preferably a parameter representing the distribution of residual stress on the surface of the steel sheet.

Alternatively, it is preferable that the parameter χ is a parameter representing a gradient of a residual stress in a width direction or a longitudinal direction of the steel sheet.

Further, α is a coefficient relating to the width of the steel sheet, n is the number of measurement data, x _W is the measurement position in the width direction, y _{L is} the stress in the longitudinal direction, x _L is the measurement position in the longitudinal direction, and X _{L is} the stress in the width direction. As y _W , the parameter と し て is preferably represented by the above (Equation 1).

Alternatively, the parameter χ is preferably a parameter determined by a moment in the width direction or the longitudinal direction of the steel sheet.

Further, assuming that the coefficient relating to the width of the steel sheet is α, the distance in the width direction from the center in the width direction to the stress measurement point is Δx _W , and the stress in the longitudinal direction is σ _L , the above parameters are: χ ₃ = 1 / α · It is preferable to be represented by W ′ · L ′ · ΣΔx _W σ _L.

In each of the above structures, it is preferable that the parameter χ is corrected according to at least one of the size of the steel sheet, the manufacturing method, and the measurement position.

Further, it is preferable that the parameter χ is calculated based on the measurement result of the temperature distribution of the steel sheet or the calculated value of the residual stress on the surface of the steel sheet.

On the other hand, in the method for manufacturing a steel sheet according to the present invention, the parameter χ is calculated from the residual stress of the steel sheet so that the variation of the deformation amount when the steel sheet is grooved is within a certain range. It is characterized in that it is determined whether or not the value falls within a predetermined range, and when the parameter χ is not within the predetermined range, the steel sheet is subjected to a correction treatment by mechanical or thermal means so as to reduce the residual stress.

Further, when the maximum value of the stress on the plate surface is σ _max , the minimum value of the stress on the plate surface is σ _min , and the correction coefficients for the width and length of the product are W ′ and L ′, respectively, It is preferable that ₁ = (σ _max −σ _min ) · W ′ · L ′.

Further, the parameter χ is preferably a parameter representing the distribution of residual stress on the surface of the steel sheet.

Alternatively, it is preferable that the parameter χ is a parameter representing a gradient of a residual stress in a width direction or a longitudinal direction of the steel sheet.

Further, α is a coefficient relating to the width of the steel sheet, n is the number of measurement data, x _W is the measurement position in the width direction, y _{L is} the stress in the longitudinal direction, x _L is the measurement position in the longitudinal direction, and X _{L is} the stress in the width direction. As y _W , the parameter と し て is preferably represented by the above (Equation 1).

Alternatively, the parameter χ is preferably a parameter determined by a moment in the width direction or the longitudinal direction of the steel sheet.

Further, assuming that the coefficient relating to the width of the steel sheet is α, the distance in the width direction from the center in the width direction to the stress measurement point is Δx _W , and the longitudinal stress is σ _L , the above parameters are χ ₃ = 1 / α · It is preferable to be represented by W ′ · L ′ · ΣΔx _W σ _L.

In each of the above methods, it is preferable that the parameter χ is corrected according to at least one of the size of the steel sheet, the manufacturing method, and the measurement position.

Further, it is preferable that the parameter χ is calculated based on the measurement result of the temperature distribution of the steel sheet or the calculated value of the residual stress on the surface of the steel sheet.

Further, the value of the residual stress is preferably an average value in the thickness direction of the steel sheet.

Alternatively, the value of the residual stress is preferably a correction value from a value on the surface of the steel sheet.

Further, it is preferable that the value of the residual stress is corrected according to at least one of the thickness, grade and manufacturing method of the steel sheet.

Further, it is preferable that the value of the residual stress is obtained at any time after rolling treatment of the steel sheet, after accelerated cooling, after hot straightening, after cold straightening and after heat treatment.

Further, it is preferable to calculate a condition under which the parameter 内 is within a predetermined range, and to perform a correction process under the calculated condition.

Further, in the correction processing, a plurality of correction conditions can be set, and when the parameter χ is not within a predetermined range, the parameter χ is recalculated on the assumption that the correction processing has been performed under the weakest correction condition. It is determined again whether the recalculated parameter 所 定 is within the predetermined range, and if the parameter χ is not within the predetermined range, the correction condition is sequentially strengthened until the parameter χ is within the predetermined range. Preferably, the recalculation of χ is repeated, and the steel sheet is subjected to the correction processing under the correction conditions when the parameter に 入 っ falls within the predetermined range.

Further, the straightening treatment of the steel sheet is preferably at least either leveler straightening or heat treatment.

The apparatus for manufacturing a steel sheet according to the present invention is characterized in that the non-uniformity of the properties of the steel sheet is determined from the residual stress of the rolled steel sheet so that the variation of the deformation amount when the steel sheet is grooved is within a certain range. Calculating means for calculating a parameter 表 す representing the parameter 、, determining means for determining whether the parameter χ is within a predetermined range, and reducing non-uniformity of characteristics when the parameter χ is not within a predetermined range. And a straightening means for straightening the steel sheet by mechanical or thermal means.

Further, the calculating means sets the maximum value of the stress on the plate surface to σ _max , the minimum value of the stress on the plate surface to σ _min , and the correction coefficients for the width and length of the product as W ′ and L ′, respectively. It is preferable to calculate a parameter さ れ る represented by χ ₁ = (σ _max −σ _min ) · W ′ · L ′.

Further, the parameter χ is preferably a parameter representing the distribution of residual stress on the surface of the steel sheet.

Alternatively, it is preferable that the parameter χ is a parameter representing a gradient of a residual stress in a width direction or a longitudinal direction of the steel sheet.

Further, the calculating means includes a coefficient α relating to the width of the steel sheet, n the number of measurement data, x _W a measurement position in the width direction, y _L a stress in the longitudinal direction, and x _L a measurement position in the longitudinal direction. Assuming that the stress in the width direction is y _W , it is preferable to calculate the parameter χ represented by the above (Equation 1).

Alternatively, the parameter χ is preferably a parameter determined by a moment in the width direction or the longitudinal direction of the steel sheet.

Further, the calculating means is: 係数₃ = 1 / α, where α is the coefficient relating to the width of the steel sheet, Δx _{W is} the distance in the width direction from the center in the width direction to the stress measurement point, and σ _L is the longitudinal stress. It is preferable to calculate a parameter _Ｗ represented by W ′ · L ′ · ΣΔx _W σ _L.

In each of the above configurations, it is preferable that the parameter χ is corrected according to at least one of the size of the steel sheet, the manufacturing method, and the measurement position.

Further, it is preferable that the parameter χ is calculated based on the measurement result of the temperature distribution of the steel sheet or the calculated value of the residual stress on the surface of the steel sheet.

Further, the calculating means obtains the value of the stress, strain or deformation at any time after the rolling treatment of the steel sheet, after the accelerated cooling, after the hot straightening, after the cold straightening and after the heat treatment. Is preferred.

Further, it is preferable that the calculating means calculates a condition under which the parameter is within a predetermined range, and performs a correction process under the calculated condition.

Further, the correction processing means can set a plurality of correction conditions, and when the parameter χ is not within a predetermined range, the parameter χ is recalculated on the assumption that the correction processing has been performed under the weakest correction condition. Then, it is determined whether the recalculated parameter χ is within the predetermined range.If the parameter χ is not within the predetermined range, the correction conditions are sequentially strengthened until the parameter に 入 る is within the predetermined range. It is preferable that the recalculation of the parameter χ be repeated to correct the steel sheet under the correction conditions at the time when the parameter に 入 っ falls within the predetermined range.

Further, it is preferable that the straightening means for the steel sheet includes at least either a roller leveler or a heat treatment furnace.

Further, in the roller leveler, the intermesh can be adjusted in a plurality of stages, and the parameter calculation means assumes that when the parameter χ is not within a predetermined range, the correction processing is performed under the weakest correction condition. Is re-calculated, and whether or not the re-calculated parameter 内 is within the predetermined range is re-determined. If the parameter χ is not within the predetermined range, the correction condition is sequentially adjusted until the parameter に 入 る is within the predetermined range. It is preferable to repeat the recalculation of the parameter し て by reinforcing the parameter and correct the steel sheet under the correction conditions when the parameter に 入 っ falls within the predetermined range.

Further, when the parameter does not fall within the predetermined range even when the parameter is corrected with the maximum capability of the roller leveler, it is preferable to perform a heat treatment with a heat treatment furnace and then perform a correction process with the roller leveler.

Further, when the parameters do not fall within the above-mentioned predetermined range even when the parameters are corrected with the maximum capacity of the roller leveler, it is preferable to perform the correction processing by the roller leveler and then perform the heat treatment by the heat treatment furnace.

[0050]

BEST MODE FOR CARRYING OUT THE INVENTION One embodiment of a steel sheet, a steel sheet manufacturing apparatus and a steel sheet manufacturing method of the present invention will be described. In the present embodiment, parameters resulting from the manufacturing conditions of the steel sheet are controlled so that the variation of the deformation amount when cutting the groove of the steel sheet is within a predetermined range.

FIG. 1 shows the configuration of the steel sheet manufacturing apparatus according to this embodiment. First, the slab is heated to 1000
The sheet is heated to about 1200 ° C., and rough rolling is performed by the first rolling device 2 until the sheet thickness reaches a first predetermined dimension. Next, for example, in the case of a 40 kg steel plate, 800 to 1100
In the case of a TMCP steel sheet, the steel sheet is cooled to about 700 to 1100 ° C., and finish rolling is performed by the second rolling device 4 until the sheet thickness becomes a second predetermined dimension. Furthermore, 40
After rapidly cooling to about 0 to 650 ° C., the shape of the steel sheet is flattened by the hot straightening device 6.

Above the hot straightening device 6, a pulse generator (hereinafter, referred to as PLG (Pulse Length Generator) which detects the leading end of the conveyed steel plate and generates a pulse signal at regular intervals.
ator)). By counting the pulse signals from the PLG 11 and multiplying the counted number of pulses by a certain length (the amount of movement of the steel sheet during the generation of one pulse), the current position from the tip of the steel sheet can be determined.

A thermometer 7 such as a thermoviewer or a scanning radiation thermometer is provided downstream of the hot straightening device 6. Fix the distance between PLG 11 and thermometer 7,
By keeping the conveying speed of the steel sheet 8 constant, the temperature distribution on the surface of the hot-corrected steel sheet 8 can be measured.

Temperature measurement data by the thermometer 7 and PLG
The information on the position of the steel sheet in the longitudinal direction by the reference numeral 11 is transferred to the server computer 15 via the digital direct controller (hereinafter, referred to as DDC) 12 and the process computer 13, respectively.

On the other hand, the rolling size, product size,
Information such as a product sampling position, a strip cutting width, and a steel plate grade is input from the host computer 19 and transferred to the server computer 15 via the line computer 14 and the process computer 13. These pieces of information are further transferred from the server computer 15 to the camber (lateral bending) prediction computer 16, the buckling prediction computer 17, and the deformation prediction computer 18.

The camber prediction computer 16 calculates the residual stress distribution of the steel sheet 8 using the temperature measurement data and the position information, for example, by the calculation method described in Japanese Patent Publication No. 4-8128 by the present applicant. The calculated residual stress distribution data is transferred to the buckling prediction computer 17 and the deformation prediction computer 18 via the server computer 15. These computers 16-18
Thus, the camber predicted value, the buckling predicted value, and the deformation predicted value at the time of groove cutting are calculated, respectively. For details on how to calculate the camber prediction value and the buckling prediction value,
For example, since it is described in Japanese Patent Application Laid-Open No. 10-56500 by the present applicant, the description is omitted here.

As an example of a deformation prediction value at the time of cutting a groove, a deformation prediction computer 18 based on a steel sheet size, a material, a calculated value of a residual stress distribution, welding conditions and a welding method at a customer, a groove cutting method, and the like. Thus, the parameter す る caused by the steel sheet manufacturing conditions is calculated, and it is determined whether or not the parameter χ is within a predetermined allowable range.

When these parameters 演算 are calculated, the deformation prediction computer 18 compares the upper limit value and the lower limit value of the allowable range predetermined according to the customer and the application transferred from the host computer 19. As a result of the comparison, when the parameter χ is not within the allowable range, straightening conditions for reducing the residual stress of the steel sheet 8 by the straightening device (roller leveler) 10 and the heat treatment furnace 9 are set. In addition,
The residual stress reducing effect of the correction by the roller leveler is described in, for example, Japanese Patent Application Laid-Open No. 9-57348 by the present applicant, so please refer to it. The setting of the correction condition will be described later.

Normally, correction (cold correction) is performed by adjusting the intermesh of the correction device (roller leveler) 10 in accordance with the set correction conditions. Further, a parameter か ら calculated from the stress distribution of the steel sheet when it is assumed that the straightening is performed under the maximum straightening condition determined from the ability of the straightening device 10.
If exceeds the allowable values (upper limit χ _c ^max and lower limit χ _c ^min ), the minimum required heat treatment conditions (heat treatment temperature and time) where parameter 演算 calculated from the residual stress distribution after heat treatment satisfies the allowable value Is set, and the residual stress is reduced using a heat treatment furnace 9 as a pretreatment for straightening.
To perform correction. The reduction of the residual stress by the heat treatment is described in, for example, Japanese Patent Application Laid-Open No. 9-78145 by the present applicant.

When setting the heat treatment conditions, the heat treatment changes the material such as the strength and the yield stress of the steel sheet. Therefore, it is necessary to determine beforehand whether or not the heat treatment is possible in consideration of the change in the material. In the steel sheet manufacturing apparatus according to the present embodiment, a table of a creep coefficient and a heat treatment possibility according to the grade of the steel sheet is provided in a memory or the like of the deformation prediction computer 18. The deformation prediction computer 18 calculates each steel sheet 8
, The following correction codes are given. For example, if the parameter χ is equal to or less than a predetermined value, no correction is required, and a correction code K = 0 indicating pass is given. Further, in the case of light pressure reduction by the correction device 10, a correction code K = 1 is given. Similarly, in the case of medium pressure correction,
Correction code K = 2 is given. In the case of under-pressure correction, a correction code K = 3 is given. When performing a heat treatment, a correction code K = 4 is given. Further, when there is no possibility that the parameter χ becomes equal to or less than the predetermined value even by the correction or the heat treatment, a correction code K = 5 representing a defect is given.

The calculation result and the judgment result (each parameter, correction code) by the deformation prediction computer 18 are transferred to the server computer 15 and stored. Further, the upper process computer 13 and the line computer 14
Will also be forwarded. The line computer 14 determines the next process based on the correction code. For example, when the correction code K = 0, the product is shipped without performing the correction and the heat treatment. On the other hand, when the correction code K = 1 to 3, the steel sheet 8 is transported to the correction device 10 and correction is performed according to the set correction code. Further, when the correction code K = 4, first, the steel plate 8
Is transported to a heat treatment furnace 9 to perform a heat treatment, and then the steel sheet 8 is further transported to a straightening device 10 for straightening under high pressure. If the correction code K = 5, it is removed from the manufacturing process.

In parallel with this, the line computer 14
Transfers the straightening and heat treatment conditions (calculation straightening conditions and calculation heat treatment conditions) of the steel sheet 8 to the straightening device 10 and the heat treatment furnace 9, respectively. The straightening device 10 and the heat treatment furnace 9 perform straightening and heat treatment in accordance with the conditions from the line computer 14, and transfer the conditions of the straightening and heat treatment (the actual straightening conditions and the actual heat treatment conditions) to the line computer 14.

Predicted deformation value (for example, the value of parameter χ),
Correction codes, heat treatment codes, operation correction conditions, operation heat treatment conditions, actual correction conditions, actual heat treatment conditions, flatness measurement results, and the like are transferred from the line computer 14 to the host computer 19 and accumulated in the quality analysis system. In this way, the residual stress distribution of the steel sheet 8 is controlled within a certain range, and it is ensured that the deformation at the time of cutting the groove at the customer is within an allowable range.

Next, the correction condition setting program by the deformation prediction computer 18 will be described with reference to the flowcharts shown in FIGS.

When the setting of the correction condition is started, the camber
The computer 16 measures temperature measurement data and position information.
To calculate the residual stress of the steel sheet (Step # 10)
0). The calculated residual stress data is used for deformation prediction computer
To the initial value of the parameter て
χ₀Is calculated (step # 105). Furthermore, deformation
The prediction computer 18 calculates the initial value of the calculated parameter χ
Value χ₀Is within a predetermined range (χ_c ^minAnd χ_c ^maxBetween)
It is determined whether it is not (Step # 110).

[0066] If the initial value chi ₀ parameter chi is within a predetermined range ^{_{(χ c min ≦ χ 0 ≦}} χ c max: Step # 110
YES), the steel sheet 8 has sufficiently small residual stress, and it is not necessary to perform a straightening process. Therefore, deformation prediction computer 18 sets the correction code K = 0 and the parameter χ = χ ₀ (Step # 115).

On the other hand, when the initial value χ ₀ of the parameter χ is not within the predetermined range (χ ₀ <χ _c ^min or χ _c ^max <χ ₀ : NO in step # 110), the steel plate 8 has a large residual stress. , Requires correction. Therefore, the deformation prediction computer 18 calculates the residual stress when it is assumed that the correction is performed under the correction condition 1, that is, under the light pressure condition by the correction device 10 (step # 120). Further, deformation prediction computer 18 performs computation of parameters chi ₁ with residual stress after straightening (Step # 125), the calculated parameter chi ₁ is within a predetermined range (between chi _c ^min and chi _c ^max) Is determined (step # 130).

[0068] If the parameter chi ₁ is within a predetermined range ^{_{(χ c min ≦ χ 1 ≦}} χ c max: YE in step # 130
S), the steel sheet 8 can reduce the residual stress within a predetermined range by performing the correction under the correction condition 1. Therefore,
Deformation prediction computer 18 sets the correction code K = 1 and the parameter χ = χ ₁ (step # 135).

[0069] If the parameter chi ₁ is not within the predetermined range (χ ₁ <χ _c ^min or χ _c ^max <χ _1: N in step # 130
O), even if the steel sheet 8 is straightened under the straightening condition 1, the residual stress is still large, and a more powerful straightening process is required. Therefore, the deformation prediction computer 18 calculates the residual stress when it is assumed that the correction is performed under the correction condition 2, that is, under the medium pressure condition by the correction device 10 (step # 140).
Further, deformation prediction computer 18 performs computation of parameters chi ₂ using residual stress after straightening (Step # 1
45), the calculated parameter χ ₂ is within a predetermined range (χ _c
It determines whether there in ^min between the chi _c ^max) (Step # 150).

[0070] If the parameter chi ₂ is within a predetermined range ^{_{(χ c min ≦ χ 2 ≦}} χ c max: YE in step # 150
S), the steel sheet 8 can reduce the residual stress within a predetermined range by straightening under the straightening condition 2. Therefore,
Deformation prediction computer 18 sets the correction code K = 2 and parameter χ = χ ₂ (Step # 155).

[0071] If the parameter chi ₂ is not within the predetermined range (χ ₂ <χ _c ^min or χ _c ^max <χ _2: N at Step # 150
O), even if the steel sheet 8 is straightened under the straightening condition 2, the residual stress is still large, and it is necessary to perform the straightening process by maximizing the ability of the straightening device 10. Thus, the deformation prediction computer 18 calculates the residual stress when it is assumed that the correction is performed under the correction condition 3, that is, under the condition of the high-pressure under the correction device 10 (step # 160). Further, the deformation predicting computer 18 uses the corrected residual stress to obtain a parameter χ
₃ performs the operation (step # 165), the calculated parameter chi ₃ determines whether within a predetermined range (between chi _c ^min and chi _c ^max) (Step # 170).

[0072] If the parameter chi ₃ is within a predetermined range ^{_{(χ c min ≦ χ 3 ≦}} χ c max: YE in step # 170
S), the steel sheet 8 can reduce the residual stress within a predetermined range by straightening under the straightening condition 3. Therefore,
Deformation prediction computer 18 sets the correction code K = 3 and the parameter χ = χ ₃ (step # 175).

[0073] If the parameter chi ₃ is not within the predetermined range (χ ₃ <χ _c ^min or χ _c ^max <χ _3: N at Step # 170
O), the residual stress of the steel plate 8 is large, and even if the ability of the straightening device 10 is maximized, the straightening is insufficient.

As described above, whether or not the heat treatment is possible is determined in advance in consideration of the change in the material of the steel sheet 8. Therefore, the deformation prediction computer 18 searches the table of whether or not the heat treatment of the steel sheet 8 is possible, and determines whether or not the steel sheet 8 can be heat-treated (step # 180).

If the steel sheet 8 cannot be heat-treated (NO in step # 180), the residual stress cannot be reduced within a predetermined range even if the steel sheet 8 has the ability of the straightening device 10, so that the deformation prediction computer 18 sets the correction code K = 5 and the parameter chi = chi ₃ represents a defective (step # 185).

When the steel sheet 8 can be heat-treated (step # 1)
(YES at 80), the deformation prediction computer 18 calculates the residual stress when it is assumed that after the heat treatment is performed in the heat treatment furnace 9, the correction is performed under the correction condition 3, that is, under the high pressure condition by the correction device 10, (see FIG. 8). Step # 190).
Further, deformation prediction computer 18 performs computation of parameters chi ₄ with residual stress after straightening (Step # 1
95), the calculated parameter chi ₄ is within a predetermined range (chi _c
determines whether the ^min between the chi _c ^max) (Step # 200).

[0077] If the parameter chi ₄ is not within the predetermined range (χ ₄ <χ _c ^min or χ _c ^max <χ _4: N at Step # 200
O), the residual stress of the steel sheet 8 is large, and even if the heat treatment is performed by the heat treatment furnace 9 and the ability of the straightening device 10 is maximized, the straightening is insufficient. Therefore, the deformation prediction computer 1
8 is a correction code K = 5 indicating a defective product and a parameter χ
= Set chi ₄ (Step # 205).

[0078] If the parameter chi ₄ is within a predetermined range ^{_{(χ c min ≦ χ 4 ≦}} χ c max: YE in step # 200
S) After the heat treatment, the steel sheet 8 can be subjected to straightening under the straightening condition 3 to reduce the residual stress within a predetermined range. Therefore, deformation prediction computer 18 sets the correction code K = 4 and the parameter chi = chi ₄ represents a heat treatment (Step # 210), and terminates the correction condition setting program.

Next, a method for evaluating a steel sheet manufactured by the steel sheet manufacturing apparatus or the steel sheet manufacturing method will be described.

In the steel sheet manufactured by the conventional steel sheet manufacturing method, the distribution of the residual stress is not controlled and is not measured. Therefore, when the residual stress of the steel sheet is large, when the customer cuts the groove of the steel sheet, the steel sheet may be deformed, bent laterally, warped, or the like exceeding an allowable value.

Accordingly, the present inventors have conducted intensive studies on the residual stress, residual strain, and material of the steel sheet in order to develop a steel sheet with less deformation during groove cutting. In the process, it was found that by controlling the parameters that represent the non-uniformity due to the manufacturing conditions of the steel sheet, it is possible to suppress the variation in the amount of deformation when cutting the groove of the steel sheet within a certain range. I got

Specifically, a plurality of steel sheets were manufactured by changing the manufacturing process, and each steel sheet was cut in a groove, and the amount of deformation and the amount of camber in the longitudinal and width directions were measured. Regarding any steel sheet, the deformation amount in the longitudinal direction and the width direction was 1 mm or less, and it was found that the influence was small. On the other hand, the camber amount reached several mm for each steel sheet.
Accordingly, in the following description, among the deformations at the time of cutting the groove, the camber is particularly described.

It is generally known that camber is generated on a steel sheet at the time of cutting a groove, not to mention inconvenient cutting conditions and poor maintenance of the cutting apparatus, but also due to uneven residual stress during the manufacturing of the steel sheet. ing. This residual stress is caused by sheet surface temperature deviation, poor flatness, improper cold straightening, and the like that occur in the steel sheet manufacturing process.

As a means for preventing the occurrence of camber, control of residual stress by cold straightening or hot treatment can be considered.
However, if the target stress state is unknown, there is a possibility that the residual stress may be controlled more than necessary, and this will not only increase the cost but also reduce the strength in the case of heat treatment and the distribution of the residual stress in the case of cold straightening. This causes a problem that non-uniformity increases.

Therefore, the correlation between the parameter relating to the residual stress on the plate surface and the deformation amount at the time of cutting the groove is found, and the parameter is controlled by changing the manufacturing method to manufacture a steel sheet with less deformation at the time of cutting the groove. I decided that. That is, if the parameter の of the steel sheet is controlled so as to be within a predetermined range, it is possible to provide a steel sheet with less deformation at the time of groove cutting.

As the parameter χ, a parameter relating to the stress deviation in the plate surface, a parameter relating to the gradient of the stress, a parameter relating to the moment of the plate surface, and the like can be considered.

Parameter 応 力 for stress deviation in the plate surface
Is, _max the maximum value of the stress plate surface sigma, minimum value sigma _min stress plate surface, a correction factor as each W 'and L' in the width and length of the products, χ ₁ = (σ _max -σ _min ) · W ′ · L ′.

FIG. 4 shows the relationship between the parameter に 関 す る relating to the stress deviation in the plate surface and the camber amount at the time of groove cutting. The horizontal axis represents the parameter χ, and the vertical axis represents the camber amount. As can be seen from FIG. 4, there is a correlation (proportional relationship) between the parameter χ and the camber amount.

Further, a parameter に 関 す る regarding the gradient of the stress
Is α, the number of measurement data is n, the measurement position in the width direction is x _W , the stress in the longitudinal direction is y _L , the measurement position in the longitudinal direction is x _L , and the stress in the width direction is y _W ,

[0090]

(Equation 2)

Is represented by

FIG. 5 shows the relationship between the parameter に 関 す る relating to the gradient of the stress and the camber amount at the time of cutting the groove. The horizontal axis represents the parameter χ, and the vertical axis represents the camber amount. As can be seen from FIG. 5, there is a correlation (proportional relationship) between the parameter χ and the camber amount.

[0093] Further, the parameter chi regarding moment of the plate surface, the coefficients in the width of the steel sheet alpha, distance [Delta] x _W in the width direction from the center in the width direction to the stress measurement point, the longitudinal stress as sigma _L, chi ₃ = 1 / α · W ′ · L ′ · ΣΔx _W σ _L

FIG. 6 shows the relationship between the parameter に 関 す る relating to the moment of the plate surface and the camber amount at the time of cutting the groove. The horizontal axis represents the parameter χ, and the vertical axis represents the camber amount. As can be seen from FIG. 6, there is a correlation (proportional relationship) between the parameter χ and the camber amount.

Incidentally, the control range of the parameter χ differs depending on the use and the allowable value of the camber at the time of cutting the groove in the customer. As an example, when performing plate joint welding in a shipbuilding manufacturer (plate length 20000 mm, plate width 4000 mm),
If a camber of 1 mm / full length occurs after the groove cutting, it is expected that the root gap will fluctuate and the penetration shape will be poor. Therefore, when trying to control the camber to 0.5 mm or less, the control range of the parameter に 関 す る regarding the stress deviation in the plate surface shown in FIG. 4 is 0.5. Similarly, the control range of the parameter に 関 す る relating to the gradient of the stress shown in FIG.
0E ^-05 . Further, the control range of the parameter に 関 す る relating to the moment of the plate surface shown in FIG.

Although the camber having the largest amount of deformation at the time of cutting a groove has been described above, the deformation amount in the longitudinal direction and the width direction is controlled in the same manner by controlling the value of the parameter to keep the amount of deformation constant. Can be controlled within the range.

Next, in order to confirm the effect of the present invention, a steel plate manufactured by the method of the present invention and a conventional steel plate were actually cut by a groove, and the generated camber amounts were compared.

First, the test piece will be described. The size of the rolled steel sheet before cutting out the test piece (original rolling size) is 20 ^t × 2520 ^W × 42000 ^L , and the size of the cut out test piece is 20 ^t × 2500 ^W × 20,000 ^L.
Met. In addition, t, W, and L represent thickness, width, and length, respectively (unit: mm).

The heating temperature in the heating furnace 1 was 1200 ° C., and the temperature at the completion of rolling was 770 ° C. The shape after the rolling was flat. The conditions of the accelerated cooling by the accelerated cooling device 5 are as follows: the temperature before cooling is 720 ° C., and the temperature after cooling is 550.
° C, 600 ° C and 650 ° C, and the cooling rate was 7 ° C / s. Further, the straightening conditions by the hot straightening device 6 were such that the set amount of reduction was 12.0 mm on the inlet side and 15.0 mm on the outlet side. The correction temperature was 540 ° C. The flatness judgment method is
The flatness was measured by a stretcher on a roller table. The result was flat.

Further, for the steel sheet A, the cold straightening condition was calculated by the deformation predicting computer 18, and cold straightening was performed by the straightening device (roller leveler) 10. The maximum straightening load of the roller leveler is 5000 tons and the straightening roll diameter is 36
Four straightening rolls of 0 × 4800 body length are arranged on the upper side, and four straightening rolls of roll diameter 360 × 4800 body length and one straightening roll of roll diameter 300 × 4800 body length 5
The book is arranged on the lower side. The correction conditions are as follows: the intermesh amount is 9.0 mm in the first pass and 7.0 in the second pass.
mm, the third pass is 5.0 mm, and the straightening speed is 20 rpm.
And Table 1 shows the details of each type of steel sheet.

[0101]

[Table 1]

In general, it is considered that the residual stress of the steel sheet A is the smallest, and the residual stresses become larger in the order of B, C and D below. The four types of steel plates (test pieces) thus obtained were each cut by a groove by gas cutting, and the camber amount was measured. The groove shape has a root face height of 3
mm, and the included angle was 70 degrees. FIG. 7 shows a comparison of the camber amount. As can be seen from FIG. 7, the steel sheet A according to the present invention
Indicates that the conventional steel plate B
In ~ D, large deformation occurred. As described above, according to the present invention, it is possible to obtain a steel sheet having a small amount of deformation when cutting a groove.

The residual stress of the steel sheet is preferably an average value in the thickness direction (average value measured or analyzed at a plurality of positions in the thickness direction). However, it is extremely complicated and difficult to actually measure or analyze the residual stress value at a plurality of positions in the thickness direction of the steel sheet. Therefore, if the residual stress value on the surface of the steel sheet can be measured and corrected to the average value in the thickness direction, the measurement or analysis of the residual stress value becomes simple and easy.
On the other hand, in general, the residual stress value on the steel sheet surface does not always coincide with the average value in the thickness direction, and greatly varies depending on the thickness, grade, manufacturing method, and the like of the steel sheet.

FIG. 8 shows the distribution of the longitudinal stress in the thickness direction for a steel sheet having an average value of the longitudinal stress in the thickness direction of zero.
Shown in Table 2 shows details of the steel sheet.

[0105]

[Table 2]

In FIG. 8, the horizontal axis represents the position of the measurement point in the sheet thickness direction (ratio to the whole: unit is dimensionless), and the vertical axis represents the stress value in the longitudinal direction of the steel sheet at each measurement point (unit: kg / mm ^2). ). As is clear from FIG. 8, the residual stress value is compression on the front and back surfaces of the steel sheet, and is significantly different from the average value. In the vicinity of the central portion in the thickness direction of the steel sheet, the residual stress value is tensile, and greatly deviates from the average value. On the other hand, in the vicinity of a position 1/4 of the plate thickness from the front surface or the back surface in the plate thickness direction of the steel plate, the residual stress value shows a value relatively close to the average value. That is, the residual stress value on the steel sheet surface does not match the average value in the thickness direction. Therefore, it is preferable to perform conversion or correction according to the thickness, grade or manufacturing method so that the residual stress on the surface of the steel sheet becomes substantially equal to the average value in the thickness direction.

Next, a steel sheet having an average value of the longitudinal stress in the thickness direction of zero (40 kg / mm ^{2 as-} rolled steel sheet)
FIG. 9 shows the relationship between the sheet thickness and the longitudinal stress on the steel sheet surface.
Shown in In FIG. 9, the horizontal axis represents the thickness (unit: mm) of each sampled steel sheet, and the vertical axis represents the residual stress value (unit: kg / mm ² ) on the surface of the steel sheet. As is clear from FIG. 9, the absolute value of the residual stress on the steel sheet surface increases as the sheet thickness increases. Therefore, by subtracting the value obtained from FIG. 9 according to the plate thickness from the measured value of the residual stress on the surface of the steel plate, the average value in the plate thickness direction can be corrected.

FIG. 10 shows the relationship between the sheet thickness and the correction value of the residual stress on the surface according to the manufacturing method and the grade of the steel sheet. In FIG. 10, the horizontal axis represents the thickness (unit: mm) of each sampled steel sheet, and the vertical axis represents the correction value (unit: kg / mm ² ) of the residual stress on the surface of the steel sheet. In the figure, “▲” indicates the value of the as-rolled steel sheet, “●” indicates the value of the accelerated cooling steel sheet, and “◆” indicates the value of the heat-treated and / or straightened steel sheet. As is clear from FIG.
A high-grade steel sheet that has been heat-treated or straightened has a smaller change in stress in the thickness direction and a smaller change in a correction value depending on the thickness than a steel sheet that has been rolled or a steel sheet that has been accelerated and cooled. Further, the change in the stress in the thickness direction also differs depending on the manufacturing method such as the as-rolled steel sheet and the accelerated-cooled steel sheet. Therefore, it is preferable to perform correction from the measured value of residual stress on the surface to the average value in the thickness direction using different correction values according to the conditions such as the manufacturing method and grade of these steel sheets.

Next, the point of measurement of the temperature distribution on the surface of the steel sheet will be discussed. Although the steel sheet manufacturing apparatus shown in FIG. 1 is configured to measure the temperature distribution on the surface of the steel sheet 8 by the thermometer 7 after the hot straightening by the hot straightening device 6, the present invention is not limited to this. Alternatively, the measurement may be performed after the rolling by the second rolling device 4 or after the accelerated cooling by the accelerated cooling device 5, but considering the necessity of correcting the measured value, the measurement after the hot straightening is desirable.

A steel sheet (product length is set to 20 m) having a supercooled temperature distribution near the end in the width direction (the temperature distribution in the longitudinal direction is assumed to be uniform) is subjected to FEM analysis to obtain a steel sheet after cooling. The longitudinal stress was calculated, and the change in the residual stress distribution when test pieces of various sizes (for example, lengths of 3 m and 8 m) were cut from the steel plate was analyzed. Table 3 shows the details of the steel sheet. FIG. 11 shows the longitudinal stress distribution measured at a plurality of positions in the width direction near the central position in the longitudinal direction of the test piece.

[0111]

[Table 3]

In FIG. 11, the horizontal axis represents the position of the measurement point in the width direction of the steel sheet (the position with respect to the width of 3000 mm: unit mm), and the vertical axis represents the value of the stress in the longitudinal direction of the steel sheet at each measurement point (unit kg). / Mm ² ). As is clear from FIG. 11, the constraint state of the steel sheet varies depending on the test piece length, and the distribution of the longitudinal stress changes. That is, focusing on a test piece having a length of 3 m, the stress in the longitudinal direction of the cut test piece changes despite the same stress distribution before cutting. Moreover, the value of the residual stress increases near the side of the steel sheet, and decreases near the center of the steel sheet. On the other hand, in the case of the test piece having a length of 8 m, the stress distribution in the longitudinal direction almost coincides with that of the product before cutting (length: 20 mm). Therefore, when the length of the test piece is short, it is necessary to calculate the stress parameter η by correcting the value of the measured residual stress to the length processed by the customer. Conversely, by cutting the test piece so that the length is at least 8 m or more, it is understood that the test piece is not affected by the length.

As described above, when the test piece is short, it is necessary to correct the measured residual stress. FIG. 12 shows the relationship between the test piece length and the correction coefficient of the residual stress. In FIG. 12, the horizontal axis represents the length (unit m) of a test piece obtained by cutting a steel plate (for example, a product having a length of 20 m), and the vertical axis represents a correction coefficient. In addition, “▲” indicates a correction coefficient (unitless dimension) of the residual stress in the vicinity of the central portion in the width direction of the steel sheet, and “●” indicates a correction value of the residual stress in the vicinity of the end portion in the width direction of the steel sheet. . The correction coefficient is a ratio (ratio) of the residual stress value at the same position in the width direction of the test piece after cutting to the residual stress value at a predetermined position from the center and the end in the width direction of the steel sheet before cutting. It is. As is clear from FIGS. 11 and 12, when the length of the test piece is short, correction is required at any position near the end in the width direction or near the center in the width direction, and the amount of correction is different. Therefore, it is preferable to correct the residual stress by multiplying the reciprocal of the correction coefficient obtained from FIG. 12 according to the test piece length.

As described above, according to the present embodiment, the groove cutting is performed according to the processing information at the customer, for example, the welding condition, the welding method, the constraint condition of the member or the allowable value of the processing accuracy, the groove cutting method, and the like. A steel sheet in which the residual stress distribution in the unprocessed state is controlled such that the deformation amount at the time is equal to or less than a predetermined allowable value is obtained.

The residual stress value or residual stress distribution on the steel sheet surface is calculated from the temperature distribution on the steel sheet surface, the value of parameter χ is calculated from the residual stress, and whether the value of parameter χ is within a predetermined range is determined. By judging, it is possible to predict the amount of deformation at the time of cutting the groove without actually cutting the groove of the steel plate.

In the above-described embodiment, as a method of controlling the residual stress level of the steel sheet, it has been described that the product is cut from the rolled steel sheet and then the mechanical straightening process is performed by the cold roller leveler. Instead of controlling the residual stress level of the steel sheet by a thermal method that directly controls the residual stress by heat treatment after cutting the product, or an indirect method that strictly controls the processes such as heating, rolling, accelerated cooling, etc. Is possible.

In the above embodiment, the calculation of the predicted deformation value in consideration of the groove cutting condition is set for each customer. However, the present invention is not limited to this. The data transfer amount can be reduced and the processing speed can be reduced. From the viewpoint of improvement, the groove cutting condition may be fixed to the strictest condition. Here, the strictest groove cutting condition is a condition under which the variation in the amount of deformation at the time of groove cutting becomes maximum, for example, when the steel plate is not constrained and the heat input during welding is large.

Further, in the above embodiment, the residual stress and the residual stress distribution of the rolled steel sheet are used as the value or parameter を representing the non-uniformity due to the manufacturing conditions of the steel sheet. However, the present invention is not limited to this. Instead, the same effect can be obtained by using the residual strain, deformation amount and the like of the rolled steel sheet.

[0119]

As described above, the steel sheet of the present invention
The parameter を representing the non-uniformity due to the manufacturing conditions of the steel sheet sets the lower limit of the allowable value to χ _c ^min and the allowable value so that the variation in the deformation amount when the steel sheet is grooved is within a certain range. Since the upper limit is set to χ _c ^max and 制 御_c ^min ≤ χ χ χ _c ^max is satisfied, when the customer cuts the steel sheet with a groove, the amount of deformation during groove cutting and its variation Is within the predicted range, and an additional process such as reworking after the groove cutting is not required, so that the workability of welding the steel sheet by the customer does not decrease.

Further, according to the steel sheet manufacturing method of the present invention, the parameter χ is calculated from the residual stress of the steel sheet so that the variation in the amount of deformation when the steel sheet is grooved is within a certain range. It is determined whether 所 定 is within a predetermined range.If the parameter な い is not within the predetermined range, the steel sheet is subjected to mechanical or thermal straightening to reduce residual stress. Can easily obtain a steel sheet having a small deformation amount.

Further, according to the steel sheet manufacturing apparatus of the present invention,
Calculating means for calculating a parameter χ representing the non-uniformity of the properties of the steel sheet from the residual stress of the rolled steel sheet so that the variation in the deformation amount when the steel sheet is grooved is within a certain range; and determining means for determining whether or not χ is within a predetermined range; and correcting the steel sheet by mechanical or thermal means so as to reduce non-uniformity of characteristics when the parameter χ is not within the predetermined range. Since it is provided with the straightening processing means, it is possible to easily manufacture a steel plate having a small amount of deformation when cutting a groove.

Further, the correction processing means can set a plurality of correction conditions, and when the parameter χ is not within a predetermined range, the parameter 再 is recalculated on the assumption that the correction processing has been performed under the weakest correction condition. Then, it is determined whether the recalculated parameter χ is within the predetermined range.If the parameter χ is not within the predetermined range, the correction conditions are sequentially strengthened until the parameter に 入 る is within the predetermined range. By repeating the recalculation of the parameter て and correcting the steel sheet under the straightening condition at the time when the parameter に 入 っ falls within the predetermined range, the steel sheet can be subjected to the residual stress distribution or the like of the hot-corrected steel sheet. Thus, optimal correction can be performed.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a configuration of a steel sheet manufacturing apparatus according to an embodiment of the present invention.

FIG. 2 is a flowchart showing a straightening condition setting program in the steel sheet manufacturing apparatus.

FIG. 3 is a continuation of the flowchart in FIG. 2;

FIG. 4 is a parameter に 関 す る regarding the maximum stress deviation in the plate surface.
FIG. 6 is a diagram showing a relationship between the measured values of camber after cutting a groove.

FIG. 5 is a diagram showing a relationship between a parameter に 関 す る relating to a gradient of stress and an actually measured value of a camber after cutting a groove.

FIG. 6 is a diagram illustrating a relationship between a parameter に 関 す る relating to a moment of a plate surface and an actually measured camber value after cutting a groove;

FIG. 7 is a diagram showing a comparison of camber amounts generated when a steel sheet according to the present invention and a conventional steel sheet are actually cut in a groove.

FIG. 8 is a diagram showing the distribution of longitudinal stress in the thickness direction for a steel sheet having an average value of the longitudinal stress in the thickness direction of zero.

FIG. 9 is a diagram showing the relationship between the thickness and the longitudinal stress on the surface of the steel sheet for a steel sheet having an average value of the longitudinal stress in the thickness direction of zero.

FIG. 10 is a diagram showing a relationship between a sheet thickness, a manufacturing method, and a correction value of a residual stress on a surface according to a grade of a steel sheet.

FIG. 11 is a view showing a longitudinal stress distribution measured at a plurality of positions in a width direction near a central position in a longitudinal direction of a test piece.

FIG. 12 is a diagram showing a relationship between a test piece length and a correction coefficient of a residual stress.

[Explanation of symbols]

 1: heating furnace 2: first rolling device 3: cooling device 4: second rolling device 5: accelerated cooling device 6: hot straightening device 7: thermometer 8: steel plate 9: heat treatment furnace 10: straightening device (roller leveler) 11 : Pulse generator (PLG) 12: Digital direct controller (DDC) 13: Process computer 14: Line computer 15: Server computer 16: Camber prediction computer 17: Buckling prediction computer 18: Deformation prediction computer

Claims (42)

[Claims] 1. The parameter χ representing the non-uniformity due to the manufacturing conditions of the steel sheet has a lower limit of the allowable value χ so that the variation of the deformation amount when the steel sheet is cut in a groove is within a certain range.
_c ^min, as the upper limit chi _c ^max tolerance, characterized in that it is controlled so as to satisfy the ^{_{χ c min ≦ χ ≦ χ c}} max steel. 2. The steel sheet according to claim 1, wherein the parameter χ is obtained from a residual stress of the steel sheet. 3. The maximum value of the stress on the plate surface is σ _max , the minimum value of the stress on the plate surface is σ _min , and the correction coefficients for the width and length of the product are W ′ and L ′, respectively, and the parameter χ is χ. _{1 = (σ max -σ min)} · W steel sheet according to claim 2, wherein the '· L' is represented by. 4. The steel sheet according to claim 2, wherein the parameter χ is a parameter representing a distribution of residual stress on the surface of the steel sheet. 5. The steel sheet according to claim 4, wherein the parameter χ is a parameter representing a gradient of a residual stress in a width direction or a longitudinal direction of the steel sheet. 6. The coefficient relating to the width of the steel sheet is α, the number of measurement data is n, the measurement position in the width direction is x _W , the stress in the longitudinal direction is y _L , the measurement position in the longitudinal direction is x _L , and the stress in the width direction is As y _W , the parameter χ is: The steel sheet according to claim 5, wherein the steel sheet is represented by: 7. The steel sheet according to claim 2, wherein the parameter χ is a parameter determined by a moment in a width direction or a longitudinal direction of the steel sheet. 8. The parameter regarding the width of the steel sheet is α, the distance in the width direction from the center in the width direction to the stress measurement point is Δx _W , and the stress in the longitudinal direction is σ _L , and the parameter is χ ₃ = 1 / α · The steel sheet according to claim 7, wherein the steel sheet is represented by W ′ · L ′ · ΣΔx _W σ _L. 9. The steel sheet according to claim 1, wherein the parameter χ is corrected according to at least one of a size, a manufacturing method, and a measurement position of the steel sheet. 10. The steel sheet according to claim 2, wherein the parameter χ is calculated based on a measurement result of a temperature distribution of the steel sheet or a calculated value of a residual stress on the surface of the steel sheet. 11. A parameter χ is calculated from a residual stress of a steel sheet so that a variation of a deformation amount when the steel sheet is grooved is within a predetermined range, and whether or not the parameter χ is within a predetermined range. And if the parameter χ is not within the predetermined range, the steel sheet is subjected to straightening treatment by mechanical or thermal means so as to reduce residual stress. 12. The parameter χ, where σ _{max is} the maximum value of the stress on the plate surface, σ _{min is} the minimum value of the stress on the plate surface, and W ′ and L ′ are correction coefficients for the width and length of the product, respectively.
Is represented by χ ₁ = (σ _max −σ _min ) · W ′ · L ′. 13. The method according to claim 11, wherein the parameter χ is a parameter representing a distribution of a residual stress on the surface of the steel sheet. 14. The steel sheet manufacturing method according to claim 13, wherein the parameter χ is a parameter representing a gradient of a residual stress in a width direction or a longitudinal direction of the steel sheet. 15. The coefficient relating to the width of the steel sheet is α, the number of measurement data is n, the measurement position in the width direction is x _W , the stress in the longitudinal direction is y _L , the measurement position in the longitudinal direction is x _L , and the stress in the width direction is As y _W , the parameter χ is the above (Equation 1)
The method for manufacturing a steel sheet according to claim 14, wherein: 16. The method according to claim 11, wherein the parameter χ is a parameter determined by a moment in a width direction or a longitudinal direction of the steel sheet. 17. The coefficient relating to the width of the steel sheet is α, the distance in the width direction from the center in the width direction to the stress measurement point is Δx _W , and the stress in the longitudinal direction is σ _L , and the parameter is: χ ₃ = 1 / α · _{W '· L' · ΣΔx W} σ steel manufacturing method of claim 16, wherein the represented by _L. 18. The parameter χ is defined as:
The method according to any one of claims 11 to 17, wherein the correction is performed according to at least one of a manufacturing method and a measurement position. 19. The steel sheet manufacturing method according to claim 11, wherein the parameter 演算 is calculated based on a measurement result of a temperature distribution of the steel sheet or a calculated value of a residual stress on the surface of the steel sheet. 20. The steel sheet manufacturing method according to claim 11, wherein the value of the residual stress is an average value in a thickness direction of the steel sheet. 21. The steel sheet manufacturing method according to claim 11, wherein the value of the residual stress is a correction value from a value on the surface of the steel sheet. 22. The method according to claim 21, wherein the value of the residual stress is corrected according to at least one of a thickness, a grade, and a manufacturing method of the steel sheet. 23. The method according to claim 11, wherein the value of the residual stress is obtained at any time after rolling treatment of the steel sheet, after accelerated cooling, after hot straightening, after cold straightening and after heat treatment. 23. The method for producing a steel sheet according to any one of the above items. 24. The steel sheet manufacturing method according to claim 11, wherein a condition under which the parameter と is within a predetermined range is calculated, and the correction process is performed under the calculated condition. 25. In the correction processing, correction conditions can be set in a plurality of stages, and when the parameter χ is not within a predetermined range,
If the parameter χ is recalculated assuming that the correction process was performed under the weakest correction condition, it is determined again whether the recalculated parameter χ is within the predetermined range, and the parameter χ is not within the predetermined range. Is to reinforce the straightening condition sequentially until the parameter に 入 る falls within the predetermined range, repeat the recalculation of the parameter 、, and straighten the steel sheet under the straightening condition at the time when the parameter に 入 っ enters the predetermined range. The method for producing a steel sheet according to any one of claims 11 to 24, characterized in that: 26. The steel sheet manufacturing method according to claim 11, wherein the steel sheet straightening treatment is at least one of leveler straightening and heat treatment. 27. An operation for calculating a parameter χ representing non-uniformity of properties of a steel sheet from residual stress of a rolled steel sheet so that variation in the amount of deformation when the steel sheet is grooved is within a certain range. Means, a determination means for determining whether the parameter χ is within a predetermined range, and mechanically or thermally reducing the steel sheet so as to reduce non-uniformity of characteristics when the parameter χ is not within the predetermined range. And a straightening means for straightening by means. 28. The calculating means, wherein the maximum value of the stress on the plate surface is σ _max , the minimum value of the stress on the plate surface is σ _min , and the correction coefficients for the width and length of the product are W ′ and L ′, respectively. 28. The steel plate manufacturing apparatus according to claim 27, wherein a parameter さ れ る represented by χ ₁ = (σ _max −σ _min ) · W ′ · L ′ is calculated. 29. The steel sheet manufacturing apparatus according to claim 27, wherein the parameter χ is a parameter representing a distribution of residual stress on the surface of the steel sheet. 30. The steel sheet manufacturing apparatus according to claim 29, wherein the parameter χ is a parameter indicating a gradient of a residual stress in a width direction or a longitudinal direction of the steel sheet. 31. The arithmetic means comprises a coefficient α relating to the width of the steel sheet, n the number of measurement data, x _W a measurement position in the width direction, y _L a stress in the longitudinal direction, and x _L a measurement position in the longitudinal direction. 4. The parameter 表 represented by the above (Equation 1) is calculated by setting the stress in the width direction as y _W.
0. A steel plate manufacturing apparatus according to item 0. 32. The apparatus according to claim 27, wherein the parameter χ is a parameter determined by a moment in a width direction or a longitudinal direction of the steel sheet. 33. The calculating means: 係数₃ = 1 / α, where α is a coefficient relating to the width of the steel sheet, Δx _{W is} a distance in the width direction from the center in the width direction to the stress measurement point, and σ _L is a longitudinal stress. 35. The steel sheet manufacturing apparatus according to claim 34, wherein a parameter で represented by W ′ · L ′ · ΣΔx _W σ _L is calculated. 34. The parameter χ is defined as:
The steel plate manufacturing apparatus according to any one of claims 27 to 33, wherein the correction is performed according to at least one of a manufacturing method and a measurement position. 35. The steel sheet manufacturing apparatus according to claim 27, wherein the parameter χ is calculated based on a measurement result of a temperature distribution of the steel sheet or a calculated value of a residual stress on the surface of the steel sheet. 36. The calculating means obtains the value of the stress, strain or deformation amount at any time after rolling treatment of the steel sheet, after accelerated cooling, after hot straightening, after cold straightening and after heat treatment. The steel plate manufacturing apparatus according to any one of claims 27 to 35, wherein: 37. The steel sheet manufacturing apparatus according to claim 27, wherein the calculating means calculates a condition that the parameter is within a predetermined range, and performs a correction process under the calculated condition. . 38. The correction processing means can set a plurality of correction conditions, and when the parameter χ is not within a predetermined range, recalculates the parameter し て on the assumption that the correction processing has been performed under the weakest correction condition. Then, it is determined again whether or not the recalculated parameter あ る is within the predetermined range.
If the parameter な い is not within the predetermined range, the correction conditions are sequentially strengthened until the parameter χ is within the predetermined range, and the recalculation of the parameter 繰 り 返 し is repeated. The steel plate manufacturing apparatus according to any one of claims 27 to 37, wherein the steel plate is subjected to a straightening process. 39. The steel sheet manufacturing apparatus according to claim 27, wherein the steel sheet straightening processing means includes at least one of a roller leveler and a heat treatment furnace. 40. The roller leveler, wherein the intermesh can be adjusted in a plurality of steps, and the parameter calculating means assumes that when the parameter χ is not within a predetermined range, the correction processing is performed under the weakest correction condition. Is re-calculated, and whether or not the re-calculated parameter 内 is within the predetermined range is re-determined. If the parameter χ is not within the predetermined range, the correction condition is sequentially adjusted until the parameter に 入 る is within the predetermined range. 4. The steel sheet is subjected to straightening processing under the straightening conditions when the parameter χ falls within the predetermined range by repeating recalculation of the parameter χ.
9. The steel plate manufacturing apparatus according to 9. 41. When the parameter does not fall within the predetermined range even after the correction with the maximum capacity of the roller leveler,
41. The steel sheet manufacturing apparatus according to claim 40, wherein after performing the heat treatment in the heat treatment furnace, the heat treatment is performed by a roller leveler. 42. When the parameter does not fall within the predetermined range even after correction with the maximum capacity of the roller leveler,
42. The steel plate manufacturing apparatus according to claim 41, wherein after the straightening process is performed by the roller leveler, the heat treatment is performed by the heat treatment furnace.