JPH1085818A - Method for preventing meandering of rolled stock in tandem rolling mill - Google Patents

Abstract

PROBLEM TO BE SOLVED: To correct the meandering quantity on the outlet side of a rolling mill, and to prevent breakage of a plate caused by drawing by changing the target value at a plate center of a center position controller on the inlet side of the rolling mill, and changing the leveling quantity of each stage stand based on the detected meandering quantity on the outlet side of the rolling mill. SOLUTION: Rolling reduction leveling setting devices 10, 11, 12 of first, second and final stage stands outputs the leveling set values 13, 14, 15 on the operation side and on the drive side of each stand to a meandering correction operating part 7 based on the rolling load on the operation side and on the drive side to be inputted from a load cell of the stands 1, 2, 3. Leveling controllers 16, 17, 18 of each stand make a regulation by operating a rolling reduction mechanism based on the leveling set value on the operation side and the drive side of each stand to be inputted from each reduction leveling setting device so that the leveling quantity operated as the difference in the rolling reduction on the operation side and the drive side of each stand.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for preventing a rolled material from meandering in a tandem rolling mill including a plurality of rolling stands, in order to prevent narrowing and breaking of the material to be rolled due to meandering.

[0002]

2. Description of the Related Art Generally, in tandem rolling of a sheet material,
Often, meandering phenomena occur in the material to be rolled due to various asymmetries on the working side and the drive side of the rolling mill and the material to be rolled. For example, when the rolled material has a plate wedge, the rolling reduction becomes large on the side where the thickness is large, and the plate meanders to the side where the rolling reduction is small. If the degree of this meandering is large, the material to be rolled comes into contact with the side guide, causing a rolling trouble.

In order to prevent meandering of a rolled material in a continuous rolling mill,
From the viewpoints of preventing mis-rolling caused by colliding with the rolling mill housing and side guides, preventing roll damage due to roll scratches caused by squeezing, preventing loss of roll change time, or preventing post-process trimming trouble and reduction in product yield This is an important technology.

[0004] As a technique for preventing meandering of a rolled material in a continuous rolling mill, various methods have conventionally been known. For example, by detecting the load difference between the rolling mill left and right due to meandering of the rolled material,
A method of controlling the left and right roll gaps according to the load difference (Japanese Patent Publication No. 63-32525), a meandering detection means for the rolled material provided on the entrance and / or the exit side of the rolling mill, If the control direction does not contradict the meandering direction of the rolled material detected by the meandering detection means,
When the control output to the rolling mill is set to “ON”, and the control direction of the roll gap in the rolling mill contradicts the meandering direction of the rolled material detected by the meandering detecting means, the control output to the rolling mill is set to “OFF”. , A device provided with a logical switch (Japanese Patent Laid-Open No. Hei 4-266414), for each rolling stand of a tandem rolling mill comprising a plurality of rolling stands, storing a leveling operation amount in a preceding rolling stand of the rolling stand; Based on the stored leveling operation amount, a change amount of the sheet wedge on the exit side of the preceding rolling stand is obtained, and based on the change amount of the sheet wedge, a meandering direction in the rolling stand is estimated. A leveling correction amount capable of correcting the meandering in the above, and adding the leveling correction amount to the leveling operation amount by the meandering control (Japanese Patent Laid-Open No. 300010 JP) have been proposed.

[0005]

SUMMARY OF THE INVENTION The above Japanese Patent Publication No. Sho 63-32
In the method disclosed in Japanese Patent Publication No. 525, if a wedge is present in the entry side sheet thickness, the load on the thick side is increased, and at the same time the rolled material tends to meander to the thin side,
Since the control acts to tighten the roll gap on the thicker side of the plate with a higher load, a malfunction occurs as the control, and the meandering is promoted instead.

The methods disclosed in JP-A-4-266414 and JP-A-4-3000010 change the leveling amount in order to correct the meandering amount immediately after rolling of the rolling stand. In the section, the meandering correction becomes insufficient, and in the case of the feed forward of the preceding rolling stand, the signal detected by the control system (for example, the rolling material speed and the reversal rate at the end of the mill) regarding the timing is the movement timing of the actual rolling material. However, there is a problem that there is no guarantee that the control errors coincide with each other, the meandering may be promoted, and the histories of these control errors are passed on to the subsequent stage. In addition, a control offset occurs in the meandering correction amount at each rolling stand, and if the leveling amount is not limited at a stand with an excessive deviation, the shape of the rolled material may be deteriorated due to abnormal one-sided pressure or cracks may occur at the plate edge. In some cases, plate breakage is induced due to occurrence of cracks. In any case, in the conventional method, the meandering correction becomes insufficient in the downstream stand, and the sheet is often broken by the narrowing.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned drawbacks of the prior art and to make it possible to correct the meandering of each rolling stand not only on each rolling stand alone, but also on a portion having the largest meandering amount, usually on the exit side of the rolling mill. By correcting the leveling amount of each rolling stand and the center position of the rolled material on the entry side of the rolling mill, a method for preventing meandering of a rolled material in a tandem rolling mill capable of preventing a sheet break due to narrowing is provided. .

[0008]

According to the present invention, there is provided a method for preventing meandering of a rolled material in a tandem rolling mill comprising a plurality of rolling stands provided with a center position control device on an entrance side. The meandering amount of the rolled material is detected at the entrance side and at the exit side of any stand. Based on the detected meandering amounts, meandering is performed with respect to the plate center target value of the center position control device and the reduction leveling set value of each stand. Is determined, and the correction amount is added to the plate center target value of the center position control device and the rolling down leveling set value of each stand. As described above, the meandering amount of the rolled material is detected at the entrance of the rolling mill and at the exit side of any stand, and based on the detected meandering amounts, the target plate center value of the center position control device and the reduction leveling set value of each stand are determined. The meandering on the exit side of the stand is corrected by obtaining a correction amount capable of correcting meandering, and adding the correction amount to the plate center target value of the plate center position control device and the reduction leveling set value of each stand. Further, it is possible to prevent the sheet from being broken due to the narrowing due to the meandering of the rolled material.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, a center position control device on the entry side of a rolling mill is generally used, and an edge detector is installed on both sides in the width direction of a material to be rolled. The center position in the width direction is detected, the deviation from the mill center is obtained, the centering roller position is automatically controlled, and the center position in the width direction of the material to be rolled is kept constant.

In the present invention, the meandering amount of the material to be rolled on the entrance side of the rolling mill and the exit side of an arbitrary stand is detected by a limit switch type, a light emitting / receiving type, a radiation type, an electromagnetic type, at both edge positions of the material to be rolled. It can be detected by installing a meandering amount detector including an end face position detector of a microwave type or the like, calculating the center position of the material to be rolled from both end face positions, and obtaining a deviation from the mill center.

The meandering control method for a tandem rolling mill according to the present invention is, for example, detecting a meandering amount of a material to be rolled which is generated on the exit side of a final stage stand downstream of the tandem rolling mill, and determining a rolling leveling amount of the final stage stand to be a material to be rolled. The meandering amount of the material to be rolled on the entry side of the tandem rolling mill is set within a predetermined stable stripping area so as to converge within a predetermined range so as not to cause deterioration in quality such as shape (flatness) and cracks. Within the range
The plate center target value of the center position control device on the entry side of the tandem rolling mill is corrected in a direction opposite to the meandering direction on the exit side of the final stand. In this case, the control gain for determining the correction amount is to consider the stand speed (reduction rate) of each stage. Furthermore, the control gain may take into account meandering characteristics (easiness of meandering or ease of meandering correction) depending on the surface roughness and material of the material to be rolled.

Further, in the present invention, the leveling set values on the working side and the drive side of each stage stand are simultaneously changed from the stand within its proper use range and having a tolerable amount of meandering. It acts to correct the meandering on the exit side. That is, in the present invention, the correction of the plate center target value on the entry side of the rolling mill and the leveling set values on the working side and the drive side of each stage stand are performed so as to correct the meandering of the material to be rolled on the exit side of the final stage stand. Can solve the problem that the meandering correction becomes insufficient as compared with the conventional downstream side stand, and the plate is broken by narrowing. Note that the plate center target value of the center position control device on the rolling mill entry side and the distribution and gain of the correction of the leveling amount on the working side and the driving side of each stage stand are optimized in advance according to the rolling mill and the rolling conditions. It is determined based on past results.

Further, according to the method of the present invention, even if the meandering detector is not installed in the mill, the meandering of the material to be rolled on the exit side is corrected before the drawing break occurs in the mill. As described above, by changing the plate center target value of the center position control device and changing the leveling set values of the working side and the drive side of each stage stand within an appropriate use range, it is possible to prevent the plate breakage due to narrowing down. it can.

[0014]

【Example】

Embodiment 1 Hereinafter, the present invention will be described in detail with reference to FIGS.
It will be described based on. FIG. 1 is a system diagram showing an example of a meandering control mechanism of the present invention, FIG. 2 is a control block diagram showing an example of a meandering correction operation unit, and FIG. 3 is a control block diagram showing another example of a meandering correction operation unit. .

In FIG. 1, reference numeral 1 denotes a first tandem rolling mill.
The step stand 2 is a second step stand, and the last step is a last step stand. The rolled material 4 is processed while moving from left to right in the figure. 5 is a meandering detector installed on the exit side of the final stage stand 3, 6 is a meandering detector installed on the entrance side of the first stage stand 1, and the meandering direction of the rolled material 4 detected by the meandering detectors 5 and 6 And the meandering amount are input to the meandering correction calculation unit 7. Reference numeral 8 denotes a center position control device provided at the front stage of the tandem rolling mill, which detects the center position in the width direction of the rolled material 4, finds the deviation from the mill center, automatically adjusts the position of the centering roller 9, and adjusts the position of the rolled material 4. Control is performed so that the center position in the width direction matches the mill center.

Reference numeral 10 denotes a reduction leveling setter of the first stage stand 1, 11 denotes a reduction leveling setter of the second stage stand 2, and 12 denotes a reduction leveling setter of the final stage 3; , 12 are based on the working-side and drive-side rolling loads input from load cells (not shown) of the respective stand stands 1, 2, and 3, and the plate thicknesses input from an upper-level computer.
2, 3 working-side and drive-side leveling set values 13,
14 and 15, and each stage stand 1, 2, 3
Are output to the meandering correction calculation unit 7. 16, 17 and 18 each stand 1
With two or three leveling controllers, each stage stand 1,2, input from each down-leveling setter 10,11,12
3, a lowering mechanism (not shown) is operated on the basis of the working side and drive side leveling set values,
The leveling amount calculated as the difference between the reduction amounts of the working side and the driving side is adjusted so as to match the leveling set value. Also, the meandering correction calculation unit 7 receives the center target value of the rolled material 4 from the center position control device 8.

As shown in FIG. 2, the meandering correction calculation unit 7
The comparator 22 compares the meandering amount 5a of the rolled material 4 input from the meandering detector 5 with a preset set value 21a stored in the storage unit 21, and the deviation is equal to or more than a certain value, for example, ± 1.
When the distance reaches 0 mm or more, the comparator 24 compares the leveling set value 15 input from the reduction leveling setting device 12 of the final stage stand 3 with the preset allowable amount 23a of the leveling amount stored in the storage unit 23, The leveling set value 14 exceeds the set allowable amount 23a of the leveling amount, and the meandering amount 6a of the rolled material 4 input from the meandering detector 6
Is compared with the preset control allowable range 25a of the center position control device stored in the storage unit 25 by the comparator 26. If the meandering amount 6a of the rolled material 4 is within the control allowable range 25a, the arithmetic unit 27 The change amount of the plate center target value of the rolled material 4 is calculated, and the setting change amount 27a is output to the center position control device 8. When the setting change amount 27a is input from the meandering correction calculation unit 7, the center position control device 8 corrects the plate center target value and operates the centering roller 9 to correct the meandering on the rolling mill exit side. ing.

With the above configuration, the deviation of the rolled material 4 from the preset set value 21a stored in the storage unit 21 at the exit side of the final stage stand 3 reaches a certain value or more, for example, ± 10 mm or more. Then, the meandering correction calculation unit 7 calculates
The comparator 24 compares the leveling set value 15 input from the rolling down leveling setter 12 of the final stage stand 3 with the preset allowable amount 23a of the leveling amount stored in the storage unit 23, and the leveling set value 14 is leveled. The meandering amount 6a of the rolled material 4 that exceeds the set allowable amount 23a and is input from the meandering detector 6 and the preset control allowable range 25a of the center position control device stored in the storage unit 25 are compared with the comparator 26. When the meandering amount 6a of the rolled material 4 is within the control allowable range 25a, the calculation unit 27 calculates the change amount of the plate center target value of the rolled material 4, and the set position change amount is sent to the center position control device 8. 27a is output to correct the target value of the plate center, the center position of the rolled material 4 is moved via the centering roller 9 in the direction of correcting the meandering on the exit side of the rolling mill, Correcting the meandering of the rolled material 4.

As shown in FIG. 3, the meandering correction calculating unit 7 includes the meandering amount 5a of the rolled material 4 input from the meandering detector 5 and the preset set value 2 stored in the storage unit 21.
1a is compared with the comparator 22. When the deviation reaches a predetermined value or more, the calculation unit 28 calculates the change amount of the target value of the plate center of the rolled material 4, and the center position control unit 8 calculates the change amount 28a of the setting. Output to correct the plate center target value.
The meandering of the rolled material 4 at the exit side of the final stage stand 3 can be corrected by moving the plate center position of the rolled material 4 in the direction in which the meandering of the rolling mill exit side is corrected.

In the above description, each stage stand 1,
Although the change of the leveling amount of a few is omitted, as described in the related art, the meandering amount of the stand changes by the change of the leveling amount, and the stand shifts to the downstream side. As a result, there is an effect of correcting the exit side meandering amount in the same manner as described above. The change in the leveling amount can be performed simultaneously with changing the center position of the rolled material 4 on the entry side of the rolling mill. In this case, the center position of the rolled material 4 is changed by the sheet center position control device 8 on the entry side of the rolling mill, and
It suffices to determine each of the gains for changing the leveling amount in a few steps. For example, the meandering correction by leveling of each of the stands 1, 2, and 3 has a small range of less than ± 5 mm, and the meandering correction by changing the center position of the entry side plate has the largest meandering (± 5 mm).
There is also a method of dividing the control range so as to correct the meandering of the stand.

Example 2 In a quadruple cold tandem mill consisting of five stands with a work roll barrel length of 1440 mm and a work roll diameter of 450 mm, the base material sheet thickness: 2.3 mm and the product sheet thickness:
When rolling a low-carbon steel cold-rolled steel strip having a thickness of 0.5 mm and a width of 1215 mm at an exit rolling speed of 1200 m / min, the meandering amount detected by a meandering detector at the exit side of the fifth stand was set in advance. Compare the set value and the deviation is + 10mm
At the time of the rolling, the plate center target value of the center position control device in the former stage of the mill was changed by −10 mm and the method of the present invention was rolled, and the meandering amount detected by the meandering detector on the exit side of the fifth stand. Compare the set value set in advance, and the deviation is + 10m
m, the level of the center of the fifth stage is changed and the meandering amount is corrected by changing the leveling amount of the fifth stand while maintaining the target value of the plate center of the center position control device in the former stage of the mill. , The meandering amount at the entrance to the rolling mill, and the change over time of the plate center target value of the center position control device (CPC) in front of the mill were measured. The result is shown in FIG. 4 by a solid line in the case of implementing the method of the present invention, and by a dashed line in the case of the conventional example.

As shown in FIG. 4A, the deviation between the meandering amount on the exit side of the fifth stand and a preset value is +10 mm.
4C, when the method of the present invention is implemented by a solid line obtained by changing the target value of the plate center of the center position control device in the preceding stage of the mill by -10 mm as shown in FIG. As described above, A in which the plate center target value was changed by −10 mm in the former stage of the mill
The meandering on the exit side of the fifth stand starts to be corrected in section B ten seconds after the time of the copy, and the meandering amount on the exit side of the fifth stand is corrected to a value close to a preset value 15 seconds later.

On the other hand, the meandering amount detected by the meandering detector on the exit side of the fifth stand is compared with a preset set value.
When the deviation becomes +10 mm, the plate center target value of the center position control device in the former stage of the mill is kept as it is, and the leveling amount of the fifth stand is changed to change the meandering amount, and the conventional example shown by the dashed line is However, the meandering amount was not corrected by changing the leveling amount of the fifth stand, and the plate was narrowed 24 seconds after the changing of the leveling amount of the fifth stand.

[0024]

According to the method for preventing meandering of a rolled material of the present invention, the plate center target value of the center position control device on the entrance side of the rolling mill is changed based on the amount of meandering detected on the exit side of the rolling mill. Since the leveling amount is changed, the meandering amount on the exit side of the rolling mill is corrected, and as a result, it is possible to prevent the sheet from being broken due to narrowing. Further, in the above embodiment, the meandering correction on the exit side of the rolling mill has been described. However, for meandering in the mill, if a meandering detector is installed at each stage stand, the stand upstream of the stand and the center position control are controlled. By performing the meandering correction operation in the apparatus, the meandering correction effect of the stand can be obtained similarly. That is, the meandering correction means in the tandem rolling mill of the present invention can be implemented not only by correcting the leveling amount of the stand alone, but also by changing the leveling amount of the upstream stand and the plate center target value of the center position control device. The stand has a function of preventing the stand from being unusually pressed down, edge cracks, shape deterioration, and the like, and has a stable meandering correction (prevention of plate breakage).

[Brief description of the drawings]

FIG. 1 is a system diagram showing an example of a meandering control mechanism of the present invention.

FIG. 2 is a control block diagram illustrating an example of a meandering correction calculation unit according to the present invention.

FIG. 3 is a control block diagram illustrating another example of the meandering correction calculation unit according to the present invention.

4A and 4B are timing charts when the meandering control is performed in the second embodiment. FIG. 4A is a deviation from the set value of the meandering amount on the exit side of the final stand, FIG. c)
The figure shows the plate center target value of the center position control device (CPC) at the front stage of the rolling mill.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 1st stage stand 2 2nd stage stand 3 Final stage stand 4 Rolled material 5, 6 Meandering detector 5a, 6a Meandering amount 7 Meandering correction calculation part 8 Center position control device 9 Centering roller 10, 11, 12 Reduction leveling setter 13, 14, 15 Leveling setting value 16, 17, 18 Leveling controller 21, 23, 25 Storage unit 21a Setting value 22, 24, 26 Comparator 23a Allowable setting amount 25a Control allowable range 27, 28 Operation unit 27a, 28a Setting Change amount

Claims (1)

[Claims] 1. A method for preventing meandering of a rolled material in a tandem rolling mill comprising a plurality of rolling stands provided with a center position control device on an entrance side, wherein the meandering of a material to be rolled is performed on the entrance side of the rolling mill and on the exit side of any stand. The amount of meandering, and based on the detected meandering amounts, determine a correction amount capable of correcting meandering with respect to the plate center target value of the center position control device and the press-down leveling set value of each stand. A meandering prevention method for a rolled material in a tandem rolling mill, wherein the mean value is added to a plate center target value of a center position control device and a reduction leveling set value of each stand.