JPH09141314A - Control of edge dropping - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten the length of the defective part of edge dropping due to a late shifting velocity of work rolls and to restrain wear of work rolls. SOLUTION: In the case of controlling edge dropping, a target manipulated variable ΔC (C2-C1) and ΔS (S2-S1) required for modifying the increase in edge dropping (EX2-EX1) into zero are respectively calculated by singly changing a work roll crossing angle and a work roll shifting position. At the time of modifying edge dropping, first, only work roll crossing is manipulated by the target manipulated variable ΔC to change the angle C1 into the angle C2. Next, the target manipulated variable ΔS of work roll shifting is manipulated to obtain the shifting position S2 while manipulating to return the work roll crossing angle into the original angle C1 so that the edge drop modifying effect amount by shift handling is offset while manipulating work roll shifting from the position S1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has a mechanism for axially shifting upper and lower work rolls in rolling a plate material, for example, a steel plate, and a mechanism for crossing the work roll alone or both the work roll and the backup roll. The present invention relates to an edge drop control method suitable for use in rolling with a good strip thickness distribution in a strip width direction using a rolling mill.

[0002]

2. Description of the Related Art A rapid change in plate thickness at a plate end (end in the plate width direction) is called an edge drop. In order to reduce the amount of this edge drop, a work having a taper roll end is conventionally used. A work roll shift method in which rolls are shifted in the width direction of the rolled material (roll axis direction) is generally performed.

For example, Japanese Unexamined Patent Publication No. 62-244506 discloses a method of setting the work roll shift position based on the plate width and the edge drop of the plate before rolling. Further, in Japanese Unexamined Patent Publication No. 4-266413, there is a method in which an edge drop meter is provided on the delivery side of the rolling mill and the work roll shift position is adjusted so that the detected width-direction plate thickness distribution and the target plate thickness distribution match. It is disclosed.

Further, in Japanese Patent Laid-Open No. 7-32002, an upper work roll and a lower work roll each having a tapered rolling portion formed at one end of the barrel portion in mutually opposite directions, and a pair of upper and lower work rolls are reinforced. A rolling mill provided with upper and lower backup rolls and provided with only the upper and lower work rolls, or roll crossing means for simultaneously crossing the upper and lower work rolls and the upper and lower backup rolls, and roll shift means for shifting the upper and lower work rolls. , The upper work roll and the lower work roll are crossed with each other so that a thrust force acts from the tapered rolling portion of the upper work roll and the lower work roll toward the non-tapered end portion, respectively, and the upper work roll and the lower work roll are crossed. Shift the work rolls in the direction of this thrust force, Shift technique of rolling a formation to strip the cross angle required strip crown control of the strip the cross angle to be completed is disclosed.

In this case, the upper work roll and the lower work roll are crossed at a required cross angle to control the plate crown of the strip, and the taper rolling portion of each of the upper work roll and the lower work roll further controls the strip material. The plate material is rolled while preventing edge drop at the edge part.

Further, in Japanese Unexamined Patent Publication No. 5-185125, in order to reduce a defective shape portion that occurs when the roll cross angle is changed, the cross angle, the shift position, and the roll bend are matched with the timing of changing the rolling conditions. The force and the settings are changed, and during these setting changes, the insufficient control amount due to the control of the cross angle and the control of the shift position, which have slow response, is compensated by the shape control of the work roll bend force with the quick response. Is disclosed. Further, when performing control by this technique, prior to changing the rolling conditions, the change amount of the cross angle, the change amount of the shift position, and the change pattern of the roll bend force are respectively obtained, and based on the results, I am trying to change those settings.

[0007]

Generally, in a continuous rolling mill, a succeeding coil is welded to a preceding coil to continuously roll many kinds of coils, but the next coil is currently rolling. When the plate width, the mother plate crown, and the like are different from those of the coil, it is necessary to change the work roll shift position at the welding point of the coil.

When the rolling conditions greatly change, such as the above-mentioned coil welding point, it is necessary to change the work roll shift position. The work roll shift for that purpose is between the work roll and the plate and the work. Since it is operated against the frictional resistance between the roll and the roll in contact with it (such as a backup roll), a considerably large force is required. Therefore, the operation speed (shift speed) at the time of shifting the work roll becomes slow, and it takes time to shift to the target position, resulting in poor responsiveness.

Therefore, the above-mentioned JP-A-62-244506 is used.
In the edge drop control method by work roll shift as disclosed in Japanese Patent Laid-Open Publication No. 4-266413, the edge drop suddenly increases during rolling, or the strip width of the succeeding material is narrowed in continuous rolling. In such a case, there is a problem in that a good edge drop cannot be obtained for the length of rolling during the work roll shift from the current work roll shift position to the desired shift position.

Further, in Japanese Patent Laid-Open No. 7-32002, when changing the shift position where the plate width changes from a wide width to a narrow width, the cross angle of the work roll is set until the shift position is completely changed. The cross angle is set to a constant value of 0.3 degrees so that the maximum thrust force acts in the shifting direction. Although the cross angle of the work roll is changed in this way, here, when changing the shift position, the cross angle is merely set so that the maximum thrust force acts in the shift direction of the work roll. .
Therefore, there is a problem that the edge drop amount changes with the change of the shift position.

Further, in the above-mentioned Japanese Patent Laid-Open No. 5-185125, the roll bend force is used to compensate for the shortage of the shape control amount while the setting of the cross angle and the shift position is being changed. Since the effect of improving the drop amount is small, there is a problem that the edge drop control cannot be performed with sufficient accuracy.

The present invention has been made to solve the above-mentioned conventional problems, and shortens the length of defective edge drop caused by a slow work roll shift speed and suppresses wear of the work roll. An object of the present invention is to provide an edge drop control method capable of achieving the above.

[0013]

According to the present invention, upper and lower work rolls each having a taper on one side end portion of rolls located on axially opposite sides, and a work roll cross mechanism for crossing the upper and lower work rolls, In the edge drop control method of the plate material at the time of plate rolling by the rolling mill equipped with the work roll shift mechanism that shifts the upper and lower work rolls respectively in the axial direction, the edge drop is performed by individually changing the work roll cross angle and the work roll shift position. The target manipulated variable required to correct each is calculated, and when the edge drop is corrected, first, the target manipulated variable is operated only on the work roll cross, and then the work roll shift operation is started, and the shift operation is performed. Work roll cloth so that the effect of edge drop correction is offset While the return to the original angle operation, by the target shift position to the work roll shifting by operating the target operation amount is obtained by solving the above problems.

[0014]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 schematically shows the relationship between a pair of upper and lower work rolls used in this embodiment and a rolling plate rolled by the work rolls.

Generally, in the work roll shift, as shown in FIG. 1, the upper and lower work rolls 101 each having a taper on one side end portion of the rolls located on the opposite sides in the axial direction are used, and the taper portion provided. Roll-shifting and rolling so that T is located inside the strip width end portion causes a change in strip thickness at the end portion of the rolled sheet 102. Therefore, by appropriately providing the work roll shift position S, the target edge drop amount can be obtained, and the edge drop can be improved.

Similarly, in the work roll cross, although not shown, a roll gap is created between the upper and lower work rolls by crossing the upper and lower work rolls with each other. Since it increases in a quadratic curve toward the end, when the work roll is rolled in a crossed state, a change in plate thickness occurs at the end of the rolled plate 102. Therefore, by properly setting the cross angle of the work roll,
A target edge drop amount can be obtained, and the edge drop can be improved.

As described above, the inventor of the present invention operates the work roll shift counter to the frictional resistance between the work roll and the plate and between the work roll and a roll (such as a backup roll) in contact with the work roll. Although the (shift speed) is slow and the response is poor, the work roll cloth can be operated almost instantaneously compared to that. The present invention has been made based on this focus.

In the present invention, first, a target operation amount (hereinafter also referred to as a target cross operation amount and a target shift operation amount, respectively) capable of achieving a desired edge drop by operating the work roll cross and the work roll shift individually. Calculate each.

As described above, in this embodiment, after the target operation amount for improving the edge drop is calculated by changing the work roll cloth and the work roll shift independently, first, the work roll cloth having a quick response is moved to the target angle. Manipulate to get the desired edge drop.
That is, since the work roll cross operation that can be performed at a higher speed than the work roll shift operation is performed first,
Compared with the case where the work roll shift is intended to improve the edge drop to the same extent, the edge drop control defective portion in the longitudinal direction of the steel sheet can be made much smaller.

However, when the work rolls are always kept in a crossed state, there is a problem that the distribution of wear changes in the roll width direction. Therefore, while the work roll cross angle is returned to the original angle, the work roll shift is performed at the same time. At this time, the return time of the work roll cloth is made to match the operation time until the target edge drop can be achieved by the work roll shift (the time required to perform the work roll shift to the target shift position).

That is, by returning the work roll cloth from the target angle to the original position, the original edge drop improving effect by the work roll cloth is reduced by the edge drop improving effect increased by the work roll shift operation. Switch.

The embodiment of the present invention will be further described below with reference to FIGS. 2 and 3 by taking as an example the case where the board width is the same but the edge drop of the mother board is increased.

Referring to FIG. 2, the procedure of one embodiment will be described. As shown in FIG. 2A, if the edge drop of the mother plate increases from the leading material EX1 to the trailing material EX2, this increase amount In order to make the increase in the edge drop after rolling corresponding to 0, the target operation amounts ΔS and ΔC that can be achieved by the work roll shift operation alone and the cross operation alone are calculated, respectively. Here, Hc represents the widthwise central plate thickness of the mother plate, and H5 represents the plate thickness at a position 5 mm inward from the plate width end.

In FIG. 2B, the shift position S1 calculated so that the edge drop increase becomes zero as described above.
From the reference angle C1 to the target angle C2, the target shift operation amount ΔS for changing from the reference angle C1 to the target angle C2 is also schematically shown in FIG. Indicated. Here, the reference shift angle C1 is a work roll cross angle that becomes a problem when the work roll wear becomes a problem when it is made larger than C1 over a long time, and the cross becomes unstable when it is made smaller than C1. Here, for example, C1 =
It can be 0.10 degrees.

Next, in order to make the increase of the edge drop zero, first, as shown in FIG. 2C, the work roll cloth having a quick response is changed from the reference cross angle C1 to the target angle C.
Operate by 2 to ΔC. The time ΔTc required for the work roll cross operation is t ₂ −t ₁ from the cross operation start time t ₁ to the end time t ₂ and at this time, the cross speed Vc is Vc = ΔC / ΔTc.

Then, at time t ₂ when the cross angle reaches the target angle C ₂ , the operation of returning the cross is started and at the same time, the work roll shift operation is started. In this shift operation, as described above, the work roll shift alone is used as the target operation amount such that the increase amount of the edge drop after rolling becomes zero, and the target shift operation amount ΔS from the shift positions S1 to S2 described above is Operate only S2-S1. At this position, the time required for the shift operation of the target operation amount ΔS is ΔTs
(T ₃ −t ₂ ), the shift speed Vs is Vs = Δ
S / ΔTs. At the same time as this shift operation, the operation of returning the cross angle from the target angle C2 to the reference angle C1 is started so that the decreasing speed of the edge drop due to the work roll shift and the increasing speed of the edge drop due to the work roll cross match. , The speed of the work roll cross operation is changed so that the work roll cross angle returns to the reference angle C1 at the time t ₃ when the work roll shift operation is completed.

According to this method, t ₁ operating the work roll cross from the angle C1 to C2 as shown in FIG. 3
Although the edge drop defect occurs temporarily only during ΔTc of up to t _2, the cross speed Vc is the shift speed Vs.
Since it is remarkably faster than the above, compared to the case of the work roll shift alone operation, the edge drop defect in the longitudinal direction of the steel plate can be far reduced. In addition, in FIG.
The edge drop amount shown in is the widthwise center plate thickness h _c on the rolling mill exit side and the plate thickness h _{5 at a} position 5 mm inside the edge.
And the difference.

Further, by setting the reference angle C1 of the normal work roll cloth to an angle at which roll wear does not become a problem, the work roll is cross-rolled at a cross angle which always obtains the target edge drop. It is possible to effectively suppress the occurrence of roll wear due to.

Next, for comparison, the conventional edge drop control for operating only the work roll shift will be described with reference to FIG. In order to reduce the edge drop increase amount to zero only by the work roll shift, as described above, the shift operation amount ΔS (= S2-S1) from the shift position S1 to S2.
) Only operate. At this time, the time required for the shift operation is ΔTs as shown in FIG.
A defect of edge drop occurs during ΔTs as shown in FIG.

On the other hand, the case where the edge drop control is performed only by the work roll cloth will be described with reference to FIG. 5. As described above, the target operation amount of the cross angle for making the edge drop increase amount zero is ΔC. At this time, the time required for the cross operation is ΔTc.

As described above, in the case of only work roll crossing, the use time ΔTc is much shorter than the time ΔTs required to make the amount of edge drop increase to zero by the above shift, but it crosses the target angle C2. If the rolling is continued in this state, the work roll will be worn.

Next, a more specific embodiment of the present invention will be described with reference to the drawings. In this embodiment, edge drop control when continuously rolling the welded portions of the coils having different plate widths will be taken up.

FIG. 6 shows all six units used in this embodiment.
A cold tandem rolling mill including a four-stage rolling stand is schematically shown. In this rolling mill, the first stand has upper and lower work rolls 611, which are similar to those shown in FIG. The backup roll 610 is arranged in four stages. Also, this first stand is based on the work roll 6 described above.
A work roll shift mechanism (not shown) for shifting 11 and a work roll cross mechanism (not shown) for crossing only the work roll 611 are provided.

In this rolling mill, the shift device (shift mechanism) of the first stand shifts the work roll 611 in response to a command from the shift operating device 601, and the cross device (cross mechanism) operates from the cross operating device 602. Upon receiving a command, the work roll 611 is crossed.

The work roll 611 is provided with a taper such that the roll diameter is reduced by 1 mm per 300 mm length in the cylinder length direction.

Further, the control unit 603, based on the rolled material information 604 such as the strip width, strip thickness, steel type, and base sheet edge drop amount of the preceding and trailing strips, the target operation amount of the work roll shift and the cloth. , Operation timing, change speed are calculated. For this calculation, a table obtained by experiments in advance, a method using a model formula, or the like can be used.

In the present embodiment, when the above rolling mill is used to continuously roll a preceding material having a plate width of 900 mm to a trailing material having a plate width of 800 mm, that is, a wide material to a narrow material, edges before and after the joint portion are joined. Perform drop control. This control will be described with reference to FIGS. 7 and 8.

During the rolling of the preceding material, the control device 603
The taper shoulder portion of the work roll calculated by
The position of the taper cutting start position indicated by is a position 50 mm inside from the edge of the plate width (the shift position at this time is S
However, when rolling the trailing material, the shift position is changed to a position 50 mm inward from the plate width end of the trailing material (the shift position at this time is defined as S2). That is, the target shift amount operation ΔS is ΔS = (900−
800) / 2 = 50 mm. Further, the required shift operation time ΔTs (t ₅ −t ₄ ) at this time is obtained from the shift speed.

Further, similarly to the case of the edge drop change of the mother plate described with reference to FIGS. 2 and 3, the operation is performed from the reference cross angle C1 at the time of rolling the preceding material to the target cross angle C2 for the following material. In this case, the target cross operation amount ΔC is calculated,
Moreover, from the cross speed, the cross operation required time ΔTc (t ₄
-T ₃ ) is calculated.

In this embodiment, the cross speed is 0.3 degrees /
Seconds, ΔC = 0.84 degrees, ΔTc = about 2.3 seconds, while the shift speed is 2 mm / sec, ΔTs = 5
0 mm / 2 mm / sec = 25 sec.

In this embodiment, the control device 603
The target operation amounts ΔC and ΔS necessary to correct the edge drop by the individual operations of the cross and shift of the work roll, the cross speed, the shift speed, the operation start / end timing, and the like are calculated in advance. Then, during rolling, at time t ₃ when a joint portion having a different strip width arrives just before the entrance side of the first stand, first, it corresponds to the target cross operation amount ΔC of the work roll cross calculated by the control device 603. A control signal for controlling the cross angle of the work roll is output to the cross operating device 602, and the cross operating device 602 outputs a command for changing the cross angle of the work roll by ΔC. In this manner, the work roll cloth having a quick response is first changed by ΔC from the reference cross angle C1 as an operation for correcting the edge drop, and the target cross angle C2 is obtained at time t ₄ . This ΔC is calculated in advance in order to make the increase amount of the edge drop zero by changing only the cloth when the work roll shift position is S1 and the plate width is changed from 900 mm to 800 mm as described above. This is the target manipulated variable for the cross angle.

Next, from the time point t ₃ above, the work roll shift target shift amount ΔS calculated by the controller 604 from the work roll shift position S 1 at the time of rolling the preceding material.
Output a control signal corresponding to the shift operation device 601 to
A command for changing the shift position of the work roll by ΔS is output from the shift operating device 601 to the shift device, and the work roll shift operation is started. At the same time, while the shift operation is being performed, the cross device sets the cross angle to the target C2 based on the change command from the cross operating device 602.
At the same time, the operation to return to the reference C1 is performed. At this time, as in the case of the mother board edge drop increase described above, the increasing speed of the edge drop improving effect by the work roll shift is made to match the decreasing speed of the edge drop improving effect by the work roll cross, and the target edge is increased. The time t at which the work roll shifting operation is completed by changing the speed of the work roll crossing operation so that the drop can be secured.
_{At 5} , make the work roll cross angle return from C2 to the reference C1.

Also in the embodiment described in detail above, FIG.
(C) in the cross angle between t ₃ ~t ₄ are operated from C1 to C2 shown, but the edge drop failure occurring temporarily as shown in FIG. 8, controlled only by the roll shifting operation The occurrence of defects can be significantly suppressed as compared with the case of performing.

As described above, the edge drop control method according to the embodiment of the present invention can significantly reduce the edge drop control failure in the longitudinal direction of the steel sheet, and when the target angle C2 is larger than the reference angle. , The work roll can be crossed more than the reference value C1 and the time for rolling can be minimized.
Long-term rolling with a cross angle larger than 1 can be prevented, and roll wear can be effectively suppressed. Even when the target angle C2 is smaller than the reference angle C1, the cross angle can be made smaller than the reference value C1 to minimize the rolling time, so that the cross angle smaller than C1 can be used for a long time. Rolling can be prevented and the work roll cloth can be prevented from becoming unstable.

That is, as described above, in the embodiment of the present invention, the increase amount ΔC (>) of the cross angle when operated independently so that the increase amount of the edge drop caused by the change of the rolling condition is zero. 0) and the increase amount of shift position ΔS
(> 0) is first calculated as the target manipulated variable, and then the cross angle of the work roll is increased from the reference value C1 to C2 by ΔC, and then the cross angle is changed from C2 to the reference value C1 by ΔC.
In this case, the decrease rate of the edge drop caused by increasing the shift position is matched with the increase rate of the edge drop caused by decreasing the cross angle so that the change amounts of the both cancel each other out. By doing so, the length of the defective portion of the edge drop can be shortened and the time for increasing the cross angle to be larger than the reference value C1 can be shortened as much as possible, so that the wear of the work roll can be suppressed. .

When the cross angle is reduced as described above, the rate of decrease may be matched with ΔC / ΔTs as a first approximation.

Further, if the edge drop is excessively reduced, the defect of edge up occurs, but in the case of such edge up, conversely, the reduction amount of the edge drop caused by the change of the rolling condition is set to zero. In the same manner, the decrease amount ΔC (ΔC> 0) of the cross angle when operated independently.
And the reduction amount ΔS (ΔS> 0) of the shift position are first calculated as target manipulated variables, and then the cross angle of the work roll is reduced from the reference value C1 to C2 by ΔC, and then the cross angle is changed from C2 to the reference value. When the value C1 is increased by .DELTA.C, the speed of edge drop increase by decreasing the shift position is matched with the speed of edge drop decrease by increasing the cross angle. Also in this case, the increasing speed of the cross angle may be matched with ΔC / ΔTs as a first approximation.

As described above, since the length of the edge drop defective portion can be shortened and the time for making the cross angle smaller than the reference value C1 can be shortened as much as possible, the work roll cloth becomes unstable. Can be prevented.

In the embodiment of the present invention, an edge drop meter is installed on the exit side of the sixth stand, for example, to obtain the edge drop amount of the rolled material, and the edge drop amount is set to a target value. You may make it control.

The present invention has been specifically described above, but the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the invention.

For example, the control method of the present invention is not limited to the above-described first stand, but may be applied to any stand, to a plurality of stands, or to all stands. . It can also be applied to a rolling mill in which a work roll and a backup roll that reinforces the work roll are crossed as a pair. Furthermore, the rolling mill is not limited to the four-high rolling mill and may be applied to the six-high rolling mill.

[0053]

As described above, according to the present invention,
It is possible to shorten the length of the defective portion of the edge drop caused by the slow shift speed of the work roll and suppress the wear of the work roll.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing the characteristics of a work roll.

FIG. 2 is a time chart for explaining the operation when the edge drop of the mother board changes.

FIG. 3 is a time chart for explaining the control effect when the edge drop of the mother board changes.

FIG. 4 is a time chart explaining the operation of only the work roll shift according to the conventional method.

FIG. 5 is a time chart explaining the operation of only the work roll cloth according to the conventional method.

FIG. 6 is an explanatory diagram showing a tandem rolling mill applied to a more specific embodiment.

FIG. 7 is a time chart for explaining the operation when the plate width changes.

FIG. 8 is a time chart for explaining the control effect when the plate width changes.

[Explanation of symbols]

 101, 611 ... Work roll 102 ... Rolled material 601 ... Shift operation device 602 ... Cross operation device 603 ... Control device 604 ... Rolled material information 610 ... Backup roll 611 ... Work roll

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazuhito Kenmochi, 1 Kawasaki-cho, Chuo-ku, Chiba, Chiba Prefecture, Technical Research Institute, Kawasaki Steel Co., Ltd. (72) Toshihiro Fukaya 1, Kawasaki-cho, Chuo-ku, Chiba, Chiba Prefecture Kawasaki Steel Co., Ltd. Chiba Steel Works (72) Inventor Tomohiro Kaneko 1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Kawasaki Steel Co., Ltd. Chiba Steel Works

Claims (1)

[Claims] 1. An upper and lower work roll in which one end of each of the rolls located on opposite sides in the axial direction is tapered, a work roll cross mechanism for crossing the upper and lower work rolls, and an upper and lower work roll in the axial direction. In the edge drop control method of a plate material when rolling a plate by a rolling mill equipped with a work roll shift mechanism that shifts, a target necessary to correct the edge drop by individually changing the work roll cross angle and the work roll shift position. When the edge drop correction effect is calculated, the target operation amount operation is performed only on the work roll cloth first, and then the work roll shift operation is started when the edge drop correction effect is offset. Operation to return the work roll cross angle to the original angle While, edge drop control method of a work roll shift, characterized in that the target shift position by operating the control input variable.