JPH07178427A - Method for controlling width of sheet in hot rolling - Google Patents

Abstract

PURPOSE:To improve dimensional accuracy and yield by enabling the estimation of the variation of width and calculation of tension control taking the variation of sheet crown ratio as a parameter and executing the setting change of a screw down contoller and sheet crown/shape controller by tension change. CONSTITUTION:The region in the vicinity of roll bite (RB) is analized using of a sheet rolling analyzing system. Width variation on the inlet side of RB and in RB is increased and decreased by the various change in rolling conditions such as a draft, length of arc of contact, tension between stands and variation of crown ratio and its rate is changed by the thickness and deflection resistance of a rolled stock. By taking the variation of sheet crown ratio as the parameter, the highly accurate estimation of the variation of the width and the calculation of proper tension control are enabled and the setting of the screw down controller and sheet crown/shape controller of each stand are changed so as to compensate effect on thickness and the amount of sheet crown by tension change. In this way, comprehensive dimensional accuracy of width, thickness, the amount of sheet crown, sheet shape, etc., is ensured.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art As a conventional strip width control method for a hot finish rolling mill, a strip width variation amount in the finish rolling mill is obtained by measurement or calculation, and is preset by a tension controller based on the measured value or the calculated value. The method of controlling the plate width by changing the tension between the stands (for example, JP-A-1-26
No. 2011), a method of controlling the plate width of the rolled material by controlling the opening of an edger installed at the entrance of the rough rolling mill and / or the finishing rolling mill is known.

Regarding the latter method of controlling the strip width by the opening degree of the edger, the strip width change amount during finish rolling is calculated based on the strip width, strip thickness, tension between stands, material temperature, and deformation resistance of the strip. A method as disclosed in Japanese Patent Laid-Open No. 62-68616 for controlling, and a crown amount or a crown change amount of a rolled material is measured or calculated, and a plate width change amount is calculated 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 63-299807.

[0004]

However, in the above-mentioned conventional method, when the influence of the plate crown is not taken into consideration or the influence of the plate crown is taken into consideration as a factor affecting the strip width in the finish rolling mill, Since it is evaluated by the absolute value of the amount of change in the crown, the relationship with the thickness of the rolled material is unclear, which makes it difficult to predict and control the width change with high accuracy.

Further, the plate thickness and the plate crown accuracy are important quality items of the rolled material like the plate width, and in order to ensure the overall dimensional accuracy, the plate width control and the plate thickness control / crown control are performed. Although decoupling is required, this is not done in the conventional method described above.

The present invention solves the above-mentioned problems by a new control method, and provides a strip width control method in hot rolling capable of performing strip width control with higher accuracy than ever before. To aim.

[0007]

SUMMARY OF THE INVENTION According to the present invention, the strip width of a rolled material between the finish rolling mill exit side or the stand is calculated or measured, and the strip width of the rolled material is determined by a tension control device in the finishing rolling mill. In the strip width control method for hot rolling to be controlled, in the finishing setup, the set values of the rolling reduction, strip crown / shape, roll peripheral speed, and tension control device at each stand of the finishing rolling mill are calculated based on the rolling reduction / crown schedule. Set value and plate thickness, rolling reduction, contact arc length, inter-stand tension of rolled material at each stand, which is required in the rolling / crown schedule.
Prediction calculation of plate width change amount that occurs between each stand and each stand based on the plate crown ratio change amount, rolling material deformation resistance, rolling material temperature and transit time between stands, and based on these calculated values, the finish rolling machine While changing the set value of the tension between each stand so that the strip width on the delivery side becomes the target strip width, the change in the strip thickness and strip crown amount of each stand caused by the rolling load change due to the change in tension and ,
It is characterized in that the set values of the rolling reduction device and the plate crown / shape control device of each stand are changed so as to correct the change amount of the plate thickness and the plate crown amount generated between the stands due to the change in tension. .

Further, according to the present invention, the strip width of the rolled material is measured by a strip width meter installed on the exit side of the finishing rolling mill or between the stands,
Based on this measured strip width, the tension between each stand is changed so that the strip width on the exit side of the finishing rolling mill becomes the target strip width, and the strip thickness of each stand caused by the change in rolling load due to this tension change and To control the reduction control device and the plate crown / shape control device of each stand so as to correct the change amount of the plate crown amount and the change amount of the plate thickness and the plate crown amount generated between the stands due to the tension change. Is characterized by.

[0009]

The principle of the present invention will be described in detail below.
First, the behavior of strip width change during finish rolling will be analyzed, and the findings obtained will be explained. The strip width change during finish rolling is roughly divided into the vicinity of a roll bite (hereinafter abbreviated as RB) as shown in FIG. It is considered that the plate width changes between the RB entrance and the RB near the RB. 7 to FIG. 11, the reduction ratios analyzed by using a plate rolling analysis system (a plate deformation analysis by three-dimensional rigid-plastic FEM and a general-purpose roll deformation analysis code by a split model are coupled) for the region near the RB. , Width of 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 can be determined by the reduction ratio, contact arc length, inter-stand tension, and crown ratio change amount C _r = C _h / h-C _H / H.
(C _H , C _h : Crown amount on the entry and exit sides; H, h: Sheet thickness on the entry and exit sides) and the like, which increase and decrease due to changes in various rolling conditions, and the ratio changes depending on the sheet thickness and deformation resistance of the rolled material. I understand that

From this, it is considered that other control such as plate thickness control and plate crown control during finish rolling may cause fluctuations in plate width as disturbances. Further, when rolling under preset rolling conditions, it is conceivable that the rolling load changes when the plate width is controlled by the tension device, and the plate thickness and the amount of plate crown change. The plate thickness and the amount of plate crown are important quality items of the rolled material, and in order to improve all dimensional accuracy including the plate width, they do not interfere with other controls such as plate thickness, plate crown and shape control. It is necessary to control the plate width with high accuracy.

Therefore, in the present invention, by using the parameter of the plate crown ratio change amount, it is possible to highly accurately predict the plate width change amount and appropriately calculate the tension control, and to change the plate thickness and the plate crown amount by changing the tension. In order to compensate for the effect on the stand, by changing the settings of the rolling reduction device and plate crown / shape control device of each stand,
We have realized plate width control that can secure overall dimensional accuracy such as plate width, plate thickness, plate crown amount, and plate shape.

Next, the process of calculating the plate width change amount in the present invention will be described. As described above, the change in plate width is shown in FIG.
It is considered that the phenomenon occurs in the three regions 1 to 3, and the plate width changing mechanism is different in each region. Therefore, in the present invention, in order to perform highly accurate prediction, a step of performing plate width prediction for each of these three areas is taken. The width change at the RB inlet 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 , Can be expressed as a function of the deformation resistance k _f and can be expressed by the following equations (1) and (2); 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).

The plate width deformation between the stands is considered to be creep deformation which occurs in a short time, as described in the 35th Plastic Working Association Lecture Collection (1984), pages 277 to 280. And the width change ΔW between the stands
₃ is expressed for each rolled material as a function of the stand-out side tension σ _o , the rolled material temperature T, the inter-stand passing time t, etc., and is calculated by the following equation (3); ΔW ₃ = ΔW ₃ (σ _o , T, t) (3).

Therefore, the total sum ΔW of the plate width change amount occurring near the RB and between the stands is as follows.
It is calculated by the equation (4); ΔW = ΔW ₁ + ΔW ₂ + ΔW ₃ (4).

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

[0016]

[Equation 1]

FIG. 6A shows a case where ΔW _c is divided by the number of stands (N-1) and is evenly distributed among the stands, and FIG. This is the case where the control setting of ΔW _c is performed with and the standard setting value is kept at other stands. In addition, (c) of FIG.

[0018]

[Equation 2]

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

[0020]

[Equation 3]

The correction amounts of the rolling control device and the plate crown / shape control device of each stand satisfying the above conditions are 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 on the entry side of the finish rolling mill or on the rough final rolling mill, the opening amount of the edger is changed based on ΔW _c to reduce the strip width control amount by the tension control device. Is also possible.

Next, the control process when the present invention is applied to the feedback control based on the strip width meter installed on the exit side of the finishing rolling mill or the finishing intermediate stand will be described with reference to the flowchart of FIG. First, the strip width W _M is measured by a strip width meter installed on the delivery side of the finishing rolling mill or between the finishing stands. Based on the measured strip width W _M and the target strip width W _T of the finishing rolling mill, the strip width control amount ΔW _c ′ in the finishing rolling mill can be obtained by the following equations (10) and (10 ′).

[0025] (i) if the finishing mill delivery side of the strip width gauge _{ΔW c '= W T -W M} ··· (10) (ii) the plate width meter finish rolling mill stand (intermediate plate width meter) in the case of

[0026]

[Equation 5]

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

[0028]

[Equation 6]

Then, the correction amounts of the rolling reduction device and the plate crown / shape control device of each stand are calculated.
According to these plate width control tension values, plate thickness, and plate crown correction values, the tension, reduction, plate crown and shape control devices are controlled simultaneously.

As described above, according to the present invention, it is possible to accurately predict the plate width change amount during finish rolling and set an appropriate tension value by the prediction formula including the plate crown ratio change amount as the plate width change factor. Since the settings of the rolling down control device and the crown control device of each stand are changed so that the influence on the plate thickness and the amount of plate crown due to the change in tension can be corrected, the plate thickness, plate crown control, etc. Highly accurate strip width control that does not interfere with the control of is realized.

[0031]

【Example】

[First Embodiment] A first embodiment of the present invention will be described below with reference to FIG. Example 1 is an example in which the present invention is applied to equipment having a strip crown gauge 6 and a strip width gauge 7 on the output side of the rough rolling mill. However, it is assumed that the plate crown meter 6 can measure the plate thickness and the plate crown amount.

After the tip of the rolled material 1 passes through the plate crown meter 6 and the plate width meter 7 installed on the exit side of the rough rolling mill, the plate thickness, the amount of plate crown, and the plate width of the rolled material 1 are measured by these measuring devices. Is measured. The arithmetic processing unit 11 determines the finish rolling mill No. based on these measured values, the target strip thickness on the delivery side of the finish rolling mill, the target strip crown amount, and the material characteristics. 1 to 7 rolling schedules for the stands, crown schedules, rolling positions for realizing these, setting values for the plate crown / shape control device, roll peripheral speed, and setting calculations for determining the tension between stands are performed. The standard rolling condition of the stand is calculated.
The arithmetic processing unit 11 further determines the finish rolling mill No. determined in the setting calculation. From No. 1 to No. 7 standard rolling conditions (reduction rate, contact arc length, inter-stand tension, crown ratio change, entry / exit plate thickness, rolled material temperature, deformation resistance, transit time between stands). Expected to occur between 1 and 7 stands and between stands

[0033]

[Equation 7]

Predict is calculated according to equation (5).

[0035]

[Equation 8]

Based on the target strip width W _T on the delivery side of the finish rolling mill and the strip width measurement amount W _E by the strip width meter 7, the strip width control amount ΔW _c is calculated by the equation (6). Based on this ΔW _c
By the tension control device of each stand (one function in the finishing rolling mill control device 10)

[0037]

[Equation 9]

The amount of change in plate thickness and the amount of change in plate crown of each stand are determined from the roll spacing and bending force of the rolling reduction device and the plate crown / shape control device (one function in the finishing rolling mill control device 10). Is calculated. The set value determined by the above calculation is
This is transmitted to the finish rolling mill control device 10, and the setting of the finish rolling mill satisfying all the target values of the strip width, strip thickness and strip crown is completed.

[Second Embodiment] A second embodiment of the present invention will be described with reference to FIG. In Example 2, a strip crown gauge 6 and a strip width gauge 7 are provided on the output side of the rough rolling mill, and an edger 4 is provided at the finish rolling mill inlet.
In addition, the present invention is applied to equipment having a strip width gauge 13 on the exit side of the finishing rolling mill. In this embodiment, the setup setting based on the edger device and the feedback control based on the plate width meter are combined. However, it is assumed that the plate crown meter 6 can measure the plate thickness and the plate crown amount.

After the leading end of the rolled material 1 passes through the plate crown meter 6 and the plate width meter 7 installed on the outlet side of the rough rolling mill, the plate thickness, plate crown amount, and plate width of the rolled material 1 are measured by these measuring devices. Is measured. As in the first embodiment, the arithmetic processing unit 11 calculates the finish rolling mill No. 1 by the setting calculation. Calculate and set the standard rolling conditions for 1 to 7 stands, and based on this standard rolling condition,

[0041]

[Equation 10]

From equation (5), the plate 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 control device 9. The edger control device 9 sets the opening amount of the edger device 4 on the entry side of the finish rolling mill based on the calculated opening amount. From the above, the calculation of the rolling conditions and the setting of the finish rolling mill control device 10 are completed.

Further, after the tip of the rolled material 1 passes through the strip width gauge 13 installed on the exit side of the finishing mill, the strip width W _M is measured and transmitted to the arithmetic processing unit 11. Based on this measured strip width W _M and the target strip width W _T on the exit side of the finish rolling mill, the strip width control amount ΔW _c ′ in the finish rolling mill is obtained from the equation (10). Based on this ΔW _c ', the tension control device of each stand

[0044]

[Equation 11]

Is calculated, and the correction amount such as the roll interval and bending force of the rolling control device and the plate crown / shape control device of each stand is calculated. The finish rolling mill control device 10 (tension, rolling reduction, plate crown / shape control device) is controlled according to the plate width control tension value and the plate thickness / plate crown correction amount.

As described above, in the equipment having the edger control device on the entrance side of the finish rolling 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 strip width gauge on the exit side of the finish rolling mill are used together. This is the case, and it is possible to reduce the correction amount by the tension control device of the finishing stand by setting the edger. Further, the above is the embodiment of the feedback control based on the strip width meter on the delivery side of the finishing rolling mill, but the same can be applied to equipment having an intermediate strip width gauge as shown in FIG. In this case, ΔW _c 'needs to be calculated by the equation (10') including the amount of change in plate width that occurs after the stand for installing the intermediate width meter. In addition, as shown in the figure, the intermediate width meter (No. 3 to 4)
The closest tension control device (between stands), for example, No. 1
~ 2, No. By performing the strip width control between a few stands, it is possible to realize the strip width control with a short dead time and excellent responsiveness.

[0047]

As described above, the present invention enables highly accurate prediction of the plate width change amount and calculation of appropriate tension control by using the parameter of the plate crown ratio change amount, and the plate change due to the tension change. By changing the settings of the rolling control device and plate crown / shape control device of each stand so as to compensate for the influence on the thickness and plate crown amount, it does not interfere with other controls such as plate thickness, plate crown / shape control. Since high-precision plate width control is performed, the dimensional accuracy of the plate width, plate thickness, and crown amount is improved compared to the conventional one, and
The effect of improving the yield is obtained.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an apparatus for carrying out a first embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of an apparatus for carrying out a second embodiment of the present invention.

FIG. 3 is a block diagram showing a configuration of an apparatus for carrying out Embodiment 2 of the present invention in another mode.

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

FIG. 5 is a flow chart showing the contents of another embodiment of the plate width control method of the present invention.

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

FIG. 7 is a graph showing the relationship between the amount of change in plate width and the rolling reduction at the RB inlet and in the RB for each outlet plate thickness h.

FIG. 8 is a graph showing the relationship between the amount of change in plate width at the RB inlet and the inside of RB and the contact arc length for each outlet plate thickness h.

FIG. 9: Amount of change in strip width at RB inlet and RB and inlet,
It is a graph which showed the relationship with the outgoing tension for every outgoing plate thickness h.

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

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

FIG. 12 is a plan view of the rolled material, schematically showing the strip width change behavior during finish rolling.

[Explanation of symbols]

1: Rolling material 2: Edger of rough rolling mill 3: Rough horizontal rolling mill 4: Edger installed in front of finishing rolling mill 5: Finishing rolling mill equipped with rolls of 7 stand 6: Rough rolling mill output side plate crown meter (Sheet gauge also used) 7: Rough rolling mill output side strip width gauge 8, 9: Edger control device 10: Finishing strip mill control device 11: Arithmetic processing unit 12: Intermediate strip width gauge 13: Finishing strip delivery side strip width gauge

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical indication location G05D 5/00 Z 8315-4E B21B 37/00 113 C (72) Inventor Yasuyuki Takamachi Chiba Prefecture 20-1 Shintomi, Futtsu-shi Nippon Steel Corp. Technology Development Division

Claims (2)

[Claims] 1. A strip width in hot rolling in which the strip width of a rolled material between the exit side or stand of a finish rolling mill is calculated or measured, and the strip width of the rolled material is controlled by a tension controller in the finish rolling mill. In the control method, in the finish setup, the set values of the reduction, plate crown / shape, roll peripheral speed, and tension control device at each stand of the finishing rolling mill are calculated based on the reduction / crown schedule, and the set values and the reduction / crown schedule are calculated. Based on the strip thickness, rolling reduction, contact arc length, inter-stand tension, strip crown ratio change, strip deformation resistance, strip temperature, and transit time between stands, each stand is calculated from each stand. And the amount of strip width change that occurs between each stand is calculated, and the strip width on the delivery side of the finish rolling mill is calculated based on this calculated value. While changing the set value of the tension between each stand so as to have the plate width, the change amount of the plate thickness and plate crown amount of each stand caused by the change of the rolling load due to the change of the tension and each stand by the change of the tension. A plate width control method, characterized in that the set values of the rolling reduction device and the plate crown / shape control device of each stand are changed so as to correct the changes in the plate thickness and the plate crown amount that occur between them. 2. The strip width in hot rolling in which the strip width of the rolled material between the finish rolling mill exit side or the stand is calculated or measured, and the strip width of the rolled material is controlled by a tension control device in the finishing rolling mill. In the control method, the strip width of the rolled material is measured with a strip width gauge installed on the exit side of the finish rolling mill or between the stands, and the strip width on the exit side of the finishing rolling mill becomes the target strip width based on this measured strip width. The tension between each stand is changed, and the change in the plate thickness and plate crown amount of each stand caused by the change in rolling load due to this tension change, and the plate thickness and plate crown generated between each stand due to the change in tension. A plate width control method characterized by controlling a rolling reduction device and a plate crown / shape control device of each stand so as to correct the amount of change in quantity.