JP3205175B2 - Strip width control method in hot rolling - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling a sheet width in hot rolling.

[0002]

2. Description of the Related Art As a conventional strip width control method for a hot finishing mill, a change in strip width in a finishing mill is obtained by measurement or calculation, and a tension control device is preset based on the measured or calculated value. A method of controlling the plate width by changing the tension between stands, which has been performed (for example,
No. 2011), a method is known in which the width of a rolled material is controlled by controlling the opening of an edger installed at the entrance of a rough rolling mill and / or a finishing rolling mill.

In the latter method of controlling the width of the sheet by the opening degree of the edger, the amount of change in the width of the sheet during finishing rolling is calculated from the width, thickness, tension between stands, material temperature and deformation resistance of the rolled material. The method disclosed in Japanese Patent Application Laid-Open No. 62-68616 for controlling, and the method of measuring or calculating a crown amount or a crown change amount of a rolled material, and calculating a sheet width change amount from the crown amount or the crown change amount. There is a method for controlling the width as disclosed in JP-A-62-296904 or JP-A-63-299807.

[0004]

However, in the above-mentioned conventional method, when the influence of the sheet crown is not taken into consideration as an influence factor of the sheet width in the finishing mill, or when the influence of the sheet crown is taken into account, Also, since the absolute value of the crown change amount was evaluated, the relationship with the rolled sheet thickness was unclear, and it was difficult to accurately predict and control the width change.

[0005] Further, sheet thickness and sheet crown accuracy are important quality items of the rolled material as well as sheet width, and in order to secure overall dimensional accuracy, sheet width control and sheet thickness control / crown control are required. Although it is necessary to achieve non-interference, this is not performed in the above-described conventional method.

An object of the present invention is to provide a strip width control method in hot rolling capable of solving the above-mentioned problems by a new control method and performing a strip width control with higher precision than before. Aim.

[0007]

According to the present invention, the sheet width of a rolled material is calculated or measured by calculating or measuring the width of a rolled material on the exit side of a finishing mill or between stands. In the hot-rolling controlled width control method, the finishing setup,
Based on the crown schedule, the set values of the rolling reduction, plate crown / shape, roll peripheral speed, and tension control device at each stand of the finishing mill are calculated.
The thickness of rolled material at each stand, contact arc length, rolling reduction, stand-to-stand tension,
Based on sheet crown ratio change, rolled material deformation resistance, rolled material temperature, and stand-to-stand transit time, these values are used as functions.
Predicting and calculating the sheet width change occurring between each stand of the finishing mill and each stand by using the sheet width change prediction formula, and using the calculated value so that the sheet width on the exit side of the finishing mill becomes the target sheet width. In addition to the change in the tension set value between the stands, the change in the plate thickness and the crown amount of each stand caused by the change in the rolling load caused by the change in the tension, and the change in the plate thickness between the stands due to the change in the tension. The present invention is characterized in that the setting values of the pressure reduction control device and the plate crown / shape control device of each stand are changed so as to correct the change in the plate crown amount.

Further, the present invention measures the width of a rolled material from a width gauge installed on the exit side of a finishing mill or between stands,
Based on this measured plate width, while changing the tension between the stands so that the plate width on the finish rolling mill exit side becomes the target plate width, the plate thickness and the thickness of each stand caused by the change in the rolling load accompanying this tension change. Controlling the roll-down control device and the plate crown / shape control device of each stand so as to correct the change in the plate crown amount and the change in the plate thickness and the plate crown amount generated between the stands due to the tension change. It is characterized by.

[0009]

The principle of the present invention will be described below in detail.
First, the sheet width change behavior during finish rolling is analyzed, and the obtained knowledge is explained. As shown in FIG. 12, the sheet width change during finish rolling is roughly divided into the vicinity of a roll bite (hereinafter abbreviated as RB). Between the stand and the stand, and it is considered that the plate width is further changed near the RB in the RB entrance and the RB. FIGS. 7 to 11 show the rolling reduction analysis of the region near the RB using a plate rolling analysis system (a combination of a plate deformation analysis code using a three-dimensional rigid-plastic FEM and a general-purpose roll deformation analysis code using a split model). It shows the width change for each of contact arc length, tension, crown ratio change and deformation resistance. From these, the amount of change in the plate width at the RB inlet and in the RB is determined by the reduction ratio, the contact arc length, the tension between stands, and the change ratio of the crown ratio _Cr = _Ch / h- _CH / H
(C _H , _Ch : Incoming and outgoing crowns; H, h: Incoming, outgoing plate thickness), etc., and changes depending on various rolling conditions, and the ratio changes depending on the thickness of the rolled material and the deformation resistance. You can see that

From this, it is considered that other controls such as thickness control and crown control at the time of finish rolling can also cause variations in the sheet width as disturbances. Further, when rolling is performed under preset rolling conditions, it is conceivable that the rolling load changes when the strip width is controlled by the tension device, and the strip thickness and strip crown amount change. Sheet thickness and sheet crown are important quality items of the rolled material. To improve all dimensional accuracy including sheet width, do not interfere with other controls such as sheet thickness, sheet crown and shape control. It is necessary to perform high-accuracy sheet width control.

Therefore, in the present invention, it is possible to accurately predict the change in the sheet width and to calculate the appropriate tension control by using a parameter called the change in the sheet crown ratio. By compensating for the effect on the stand, by changing the settings of the screw down control device and the plate crown / shape control device of each stand,
Sheet width control has been realized that can ensure comprehensive dimensional accuracy such as sheet width, sheet thickness, sheet crown amount, and sheet shape.

Next, a description will be given of a process of calculating the amount of change in the plate width according to the present invention. As described above, the change in the plate width is shown in FIG.
It occurs in three regions as shown in 2 and it is considered that the plate width change mechanism differs in each region. Therefore, in the present invention, in order to perform high-precision prediction, a step of performing plate width prediction for each of the three regions is performed. The width change amount in the RB entrance and RB is ΔW
_1, when [Delta] W _2, [Delta] W _1, the [Delta] W ₂ the above analysis result, exit side thickness h, a reduction ratio r, the contact arc length l _d, input and exit side tension sigma _i, sigma _o, crown ratio change C _r , expressed as a function of the deformation resistance k _f, the following (1), (2) to become as _{formula; ΔW 1 = ΔW 1 (h} , r, l d, σ i, σ o, C r, k f) · .. (1) ΔW ₂ = ΔW ₂ (h, r, l _d , σ _i , σ _o , C _r , k _f ) (2).

[0013] Further, the plate width deformation between the stands is considered to be a creep deformation occurring in a short time as described in the 35th Joint Lecture on Plastic Working (1984), pp. 277-280. And the width change ΔW between the stands
₃ is expressed as a function of the stand-side exit side tension σ _o , the rolled material temperature T, the stand-to-stand passage time t, etc., for each rolled material, and is calculated as in the following equation (3); ΔW ₃ = ΔW ₃ (σ _o , T, t) (3).

Therefore, the total sum .DELTA.W of the plate width change occurring near the RB and between the stands is as follows.
ΔW = ΔW ₁ + ΔW ₂ + ΔW ₃ (4).

The sheet width control process based on the sheet width prediction formulas (1) to (4) will be described below with reference to the flowcharts shown in FIGS. FIG. 4 shows plate width control when the present invention is applied to a finish setup. First, the sheet thickness, sheet crown amount, and sheet width on the entrance side of the finishing mill are measured or calculated. Based on the thickness and crown of the finishing mill at the entrance and the target thickness and crown at the exit of the finishing mill and the material properties, the standard rolling schedule and the standard crown schedule for each stand of the finishing mill are determined. The roll spacing (roll-down position) for realizing these, the set values of the sheet crown / shape control device, the roll peripheral speed, and the stand-to-stand tension are calculated and calculated. The setting values of the shape control device, roll peripheral speed and tension control device, that is, various control devices in the finishing mill, are determined. Here, the set value of the sheet crown / shape control device is a bending force or the like, and indicates the cross angle and the shift amount in the case of equipment having a roll cross or shift function. The above set values and the thickness, rolling reduction, contact arc length, stand-to-stand tension, crown ratio change, temperature, calculated in the rolling schedule and crown schedule
Deformation resistance and transit time between stands are represented by h _s , r _s ,
_{l ds, σ is, C rs} , T s, k fs, and the _{t s, (1) ~ (} 4)
From the formula, finishing mill No. i stand and No. i ~
No. Expected to occur between i + 1 stands

[0016]

(Equation 1)

FIG. 6A shows a case in which ΔW _c is divided by the number (N−1) between stands and is evenly distributed in each stand. FIG. In this case, the control setting of ΔW _c is performed, and the reference setting value is maintained at other stands. In addition, FIG.

[0018]

(Equation 2)

Further, when the plate width control amount ΔW _c is relatively small, the plate width is controlled only by the preceding stand, and when ΔW _c is large, the control range can be extended to the subsequent stand. The width control amount of each stand obtained as described above

[0020]

(Equation 3)

The correction amount of the rolling control device and the plate crown / shape control device of each stand that satisfies is calculated, and the set values such as the roll interval and the bending force are changed.

[0022]

(Equation 4)

Further, in the case of equipment having an edger at the entrance to the finishing mill or at the rough and final rolling mill, the opening degree of the edger is changed based on ΔW _c to reduce the width control amount of the tension control device. Is also possible.

Next, a control process in the case where the present invention is applied to feedback control based on a width gauge installed on the exit side of a finishing mill or on a finishing intermediate stand will be described with reference to the flowchart of FIG. First, the plate width W _M is measured by the sheet width meter installed between the finish rolling mill exit side or finishing stand. Based on the measured strip width W _M and finishing mill exit side target plate width W _T, sheet width control amount [Delta] W _c in the finishing mill 'is the following (10), (10' is determined as) below.

(I) In the case of a width gauge on the exit side of the finishing mill ΔW _c ′ = W _T −W _M (10) (ii) A width gauge between the finishing mill stands (intermediate width gauge) in the case of

[0026]

(Equation 5)

However, when the board width is measured by an intermediate board width gauge (installed between No. M-1 to M stands), it occurs after the width gauge installation stand.

[0028]

(Equation 6)

Is calculated, and the correction amount of the rolling-down control device and the plate crown / shape control device of each stand is calculated.
In accordance with the sheet width control tension value and the sheet thickness and sheet crown correction values, the tension, rolling down, sheet crown and shape control devices are simultaneously controlled.

As described above, according to the present invention, the prediction formula including the plate crown ratio change amount as the plate width change factor enables highly accurate prediction of the plate width change amount during finish rolling and setting of an appropriate tension value. The setting of the roll-down control device and the crown control device of each stand has been changed so as to make it possible and to correct the effect of the tension change on the plate thickness and the plate crown amount. High-precision plate width control that does not interfere with the control of.

[0031]

【Example】

Embodiment 1 Embodiment 1 of the present invention will be described below with reference to FIG. Example 1 Example 1 is an example in which the present invention is applied to equipment having a sheet crown meter 6 and a sheet width meter 7 on the rough rolling mill exit side. However, the sheet crown meter 6 can measure the sheet thickness and the sheet crown amount.

After the leading end of the rolled material 1 has passed through the strip crown meter 6 and the strip width meter 7 installed on the exit side of the rough rolling mill, these measuring devices measure the strip thickness, strip crown amount and strip width of the rolled strip 1. Is measured. The arithmetic processing unit 11 finishes the finishing mill No. on the basis of these measured values, the target sheet thickness, the target sheet crown amount and the material properties on the exit side of the finishing mill. The rolling schedule and crown schedule at the 1 to 7 stands, and the rolling position for realizing these, the setting value of the plate crown / shape control device, the roll peripheral speed, and the setting calculation for determining the tension between stands are calculated. The standard rolling conditions of the stand are calculated.
The arithmetic processing unit 11 further sets the finishing mill No. determined in the setting calculation. From the standard rolling conditions (rolling reduction, contact arc length, tension between stands, change in crown ratio, inlet / outlet thickness, rolled material temperature, deformation resistance, time between stands) at Nos. 1 to 7 stands. Expected to occur between 1-7 stands and between stands

[0033]

(Equation 7)

Is calculated according to equation (5).

[0035]

(Equation 8)

[0036] and by finish rolling mill exit side target plate width W _T and the plate width meter 7 on the basis of the sheet width measured quantity W _E, by (6), to calculate the sheet width control amount [Delta] W _c. Based on this ΔW _c ,
By the tension control device of each stand (one function in the control device 10 of the finishing mill)

[0037]

(Equation 9)

From this, the thickness change and crown change of each stand are obtained, and the roll spacing and bending force of the rolling reduction control device and the plate crown / shape control device (one of the functions of the finishing mill control device 10) are obtained. Is calculated. The set value determined by the above calculation is
The setting is transmitted to the finishing mill control device 10 and the setting of the finishing mill satisfying all the target values of the sheet width, the sheet thickness, and the sheet crown is completed.

Second Embodiment A second embodiment of the present invention will be described with reference to FIG. In Example 2, a sheet crown meter 6 and a sheet width meter 7 were provided on the exit side of the rough rolling mill, and an edger 4 was provided at the entrance of the finishing mill.
This is an example in which the present invention is applied to equipment having a width gauge 13 on the exit side of a finishing mill. In this embodiment, the setup setting based on the edger device and the feedback control based on the width gauge are combined. However, it is assumed that the sheet crown meter 6 can measure the sheet thickness and the sheet crown amount.

After the leading end of the rolled material 1 has passed through the strip crown meter 6 and the strip width meter 7 provided on the exit side of the rough rolling mill, the thickness, the crown amount and the strip width of the rolled material 1 are measured by these measuring devices. Is measured. As in the first embodiment, the arithmetic processing unit 11 performs finishing rolling mill No. Calculate and set the standard rolling conditions at stands 1 to 7, and based on these standard rolling conditions,

[0041]

(Equation 10)

From equation (5), the width control amount ΔW _{c is} obtained from equation (6).
Is calculated. From this ΔW _c , the opening amount of the edger device is calculated and transmitted to the edger controller 9. The edger control device 9 sets the opening amount of the edger device 4 on the entry side of the finishing mill based on the calculated opening amount. Thus, the calculation of the rolling conditions and the setting of the finishing mill control device 10 are completed.

[0043] Further, after passing the plate width meter 13 installed in the rolling mill exit side tip of the strip 1 is finishing, it is transmitted to the processing unit 11 the plate width W _M is measured. The measurement plate based on the width W _M and finishing mill exit side target plate width W _T, sheet width control amount [Delta] W _c 'of the finishing mill is obtained from (10). Based on this ΔW _c ′, the tension control device of each stand

[0044]

[Equation 11]

Is calculated, and the amount of correction such as the roll interval and the bending force of the rolling control device and the plate crown / shape control device of each stand is calculated. In accordance with the sheet width control tension value and the sheet thickness / sheet crown correction amount, the finishing mill control device 10 (tension, rolling down, sheet crown / shape control device) is controlled.

In the above, in the equipment having the edger control device on the entrance side of the finishing mill, the setting of the edger opening amount based on the strip width prediction formula and the feedback control by the tension control device based on the width gauge on the exit side of the finishing mill are used together. This is the case, and the amount of correction by the tension control device of the finishing stand can be reduced by performing the edger setting. Although the above is an embodiment of the feedback control based on the width gauge on the exit side of the finishing mill, the present invention can be similarly applied to equipment having an intermediate width gauge as shown in FIG. In this case, ΔW _c ′ needs to be obtained by the equation (10 ′) including the plate width change occurring after the intermediate width meter installation stand. Also, as shown in the figure, the intermediate width meter (No. 3 to 4)
(Between the stands). 1
~ 2, No. By performing plate width control between two or three stands, it is possible to realize plate width control with little dead time and excellent responsiveness.

[0047]

As described above, the present invention makes it possible to use a parameter called the sheet crown ratio change amount to make it possible to predict the sheet width change amount with high accuracy and calculate proper tension control. By changing the settings of the rolling control device and the crown / shape control device of each stand so as to compensate for the effect on the thickness and the crown thickness, it does not interfere with other controls such as thickness, crown and shape control High-precision control of the width of the sheet has improved the dimensional accuracy of the width, thickness, and crown amount compared to the past, and
The effect of improving the yield can be obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of an apparatus that implements a first embodiment of the present invention.

FIG. 2 is a block diagram illustrating a configuration of an apparatus that implements a second embodiment of the present invention.

FIG. 3 is a block diagram illustrating a configuration of an apparatus that implements Embodiment 2 of the present invention in another mode.

FIG. 4 is a flowchart showing the contents of one embodiment of the sheet width control method of the present invention.

FIG. 5 is a flowchart showing the contents of another embodiment of the sheet width control method of the present invention.

FIG. 6 is a graph showing an example of distribution of a plate width control amount ΔWc in each stand according to the present invention.

FIG. 7 is a graph showing the relationship between the sheet width change amount and the reduction ratio in the RB inlet and the RB for each outlet side sheet thickness h.

FIG. 8 is a graph showing a relationship between a plate width change amount in the RB entrance and the RB and a contact arc length for each exit side plate thickness h.

FIG. 9 is a diagram showing a change in the width of the plate at the RB entrance and the RB;
It is the graph which showed the relationship with delivery side tension for every delivery side board thickness h.

FIG. 10 is a graph showing the relationship between the amount of change in the width of the plate and the amount of change in the crown ratio at the entrance of the RB and in the RB for each exit side plate thickness h.

FIG. 11 is a graph showing the relationship between the amount of change in plate width at the RB entrance and in the RB and the deformation resistance.

FIG. 12 is a plan view of a rolled material, and schematically shows a width change behavior during finish rolling.

[Explanation of symbols]

1: rolled material 2: rough rolling mill edger 3: rough horizontal rolling mill 4: edger installed in front of finishing rolling mill 5: finishing rolling mill equipped with rolls of 7 stands 6: rough rolling mill exit side sheet crown meter (Also used as thickness gauge) 7: Outboard width gauge for rough rolling mill 8, 9: Edger control device 10: Finishing mill control device 11: Operation processing device 12: Intermediate width gauge 13: Finishing mill width measurement

──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Yasuyuki Takamachi 20-1 Shintomi, Futtsu-shi, Chiba Nippon Steel Corporation Technology Development Division (56) References JP-A-1-99710 (JP, A) JP-A-5-285516 (JP, A) JP-A-1-262013 (JP, A) JP-A-5-285517 (JP, A) JP-A-5-154527 (JP, A) 31325 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B21B 37/22 B21B 37/00

Claims (2)

(57) [Claims] 1. A strip width in hot rolling in which a strip width of a rolled material is calculated or measured by calculating or measuring a roll width of a rolled material on the exit side of a finish rolling mill or between stands, and the strip width of the rolled material is controlled by a tension control device in the finish rolling mill. In the control method, in the finishing set-up, the set values of the reduction, sheet crown / shape, roll peripheral speed, and tension control device at each stand of the finishing mill are calculated based on the reduction / crown schedule, and the setting calculation and the reduction / crown schedule are performed. These values are calculated based on the thickness of the rolled material at each stand, the contact arc length, the rolling reduction, the tension between stands, the change in strip crown ratio, the deformation resistance of the rolled material, the temperature of the rolled material at each stand, and the time between the stands. Sheet width change prediction formula
Is used to predict and calculate the change in the width of each finishing mill stand and each stand, and the tension between the stands is adjusted based on the calculated value so that the width of the sheet on the exit side of the finishing mill becomes the target width. And the amount of change in the thickness and crown of each stand caused by the change in the rolling load due to the change in tension, and the change in the thickness and crown of each stand caused by the change in tension. A plate width control method characterized by changing set values of a pressure reduction control device and a plate crown / shape control device of each stand so as to correct the difference. 2. The sheet width in hot rolling in which the sheet width of the rolled material is calculated or measured by calculating or measuring the width of the rolled material on the exit side of the finishing mill or between the stands, and the tension control device in the finishing mill controls the sheet width of the rolled material. In the control method, the width of the rolled material is measured by a width gauge installed on the exit side of the finishing mill or the stand, and based on the measured width, the width of the exit side of the finishing mill becomes the target width. In addition to the change in the tension between the stands, the change in the plate thickness and the sheet crown amount of each stand caused by the change in the rolling load accompanying the change in the tension, and the sheet thickness and the sheet crown generated between the stands due to the change in the tension. A method of controlling a width of a sheet, comprising controlling a pressure reduction control device and a sheet crown / shape control device of each stand so as to correct a change in the amount.