JPH10272506A - Shortest time rolling method for reverse mill - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To improve the production efficiency by reducing the switching time from the release from the previous pass to the next pass in the automatic switching operation of the reverse mill such as hot rolling of thick plates. A search of the current reduction positioning completion time than pressing position change amount x from pressing position to the pressing position of the next pass t _s of the roll, when the t _s is greater than a predetermined value, the rolled currently rolling When the remaining length of the wood becomes a predetermined length L _1, and starts the deceleration of the rolling velocity V, and initiate a change of pressure position of the roll at which the rolled material is released chewing from a roll, to stop the material to be rolled After that, the rolled material is turned back so that the roll pressing positioning completion timing coincides with the biting timing of the material to be rolled in the next pass. If t _s is less than the predetermined value, when the remaining length of the rolled material becomes a predetermined length L _2, it starts to decelerate, performs forward turning continuously to the reduction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shortest time rolling method for shortening a rolling time in a reverse mill which is installed in a hot rolling step of a thick plate and performs return rolling in several passes.

[0002]

2. Description of the Related Art For example, in hot rolling of a thick plate, as shown in FIG. 9 (a), a quadruple reversible rolling mill comprising a pair of upper and lower work rolls 1, 2 and backup rolls 3, 4 is used. After the slab 7 heated to a predetermined temperature in the heating furnace is rolled in the forward direction, the work roll gap is narrowed and the work is rolled in the reverse direction, and this is repeated a plurality of times to obtain a steel sheet having a predetermined thickness. A pair of upper and lower work rolls 1 and 2 are driven to rotate by a rotation drive motor 5, respectively, and the upper work roll 1 and the upper backup roll 3 are moved up and down with respect to the fixed lower work roll 2 and the lower backup roll 4 by a pressing-down device. To change the work roll gap.
The screw-down device employs an electric screw type using a screw-down motor 6 as a drive source or a hydraulic type using a hydraulic cylinder.

[0003] The operation of such a reverse mill has conventionally been
The manual switching operation was the mainstream, but recently, the automatic switching operation has been implemented. In this automatic switching operation, as shown in FIG. 9 (b), when the slab 7 of the positive path is released from the work rolls 1 and 2, the rolling position change is performed, and the rolling position change is completed (the rolling APC is completed). At the time of APC (Automatic Position Control), the slab 7 was cut back and bitten into the work rolls 1 and 2. Looking at this operation on the time axis, the graph shown in FIG. 10 is obtained. In FIG. 10, the slab is rolled in the positive direction at a rolling speed V _T is released biting from the work roll, which is detected by such load variation of the load cell of the screw down device, deceleration and reduction of the rolling speed V The position change is started, and then the slab that has been decelerated and stopped is turned back at the timing of the completion of the reduction APC,
As the slab at the reference speed V _B is lower than the rolling speed V _T rate biting the work rolls, and controlling the rolling speed V in the reverse path.

[0004]

However, in the conventional automatic reversing operation as described above, the rolling speed V starts to be reduced at the time when the slab is released and the rolling position starts to be changed, and the timing of the completion of the rolling APC is started. In this case, there is a problem that a time (return time) T from the release of the previous pass to the subsequent pass is required. Further, the biting, since the insufficient torque when the slab is not bitten by the rotational speed following the reference speed V _B state of the rotational driving motor of the work rolls, it is necessary to bitten at the reference speed V _B, more time It is a factor of this.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem, and an object of the present invention is to reduce the time required for turning over from the release of the previous pass to the engagement of the next pass in the automatic return operation of the reverse mill. An object of the present invention is to provide a method for rolling a reverse mill in the shortest time that can shorten the time and improve the productivity.

[0006]

In order to achieve the above object, according to the present invention, there is provided a reverse mill in which a roll rolling position is changed for each pass to perform several pass turning rolling.
As shown in FIG. 1, the rolling speed V is started to be reduced before the roll of the material being rolled is released, and the roll reduction position is started at the time when the roll is released from the roll during this reduction. The rolled material is turned back so that the roll pressing positioning completion timing and the roll biting timing of the material to be rolled in the next pass coincide.

For example, as shown in FIG. 1 (a), a roll-down positioning completion time t _s1 is obtained from a roll-down position change amount x from the current roll-down position to the roll-down position of the next pass. _{When s1} is larger than a predetermined value (when the reduction position change amount x is large and there is a margin for switching back), FIG.
As shown in, the remaining length L ₁ of the material to be rolled, such as rolling speed V during release chewing roll the material to be rolled becomes around reference speed V _B
And the remaining length L of the material to be rolled currently being rolled is calculated as the remaining length L
_When the rolling speed V becomes ₁ , the rolling speed V starts to be reduced, and at the time when the material to be rolled is released from the roll during this reduction, the change in the roll reduction position is started. The rolled material is turned back so that the positioning completion timing and the rolled material biting timing in the next pass coincide.

Further, as shown in FIG. 1B, a rolling-down positioning completion time t _s2 is obtained from a rolling-down position change amount x from the current rolling-down position of the roll to the rolling-down position of the next pass. _{When s2} is smaller than a predetermined value (when the reduction position change amount x is small and there is no margin for turning back), as shown in FIG. 4, the roll reduction positioning completion timing coincides with the biting timing of the material to be rolled in the next pass. the residue length L ₂ of the rolled material is calculated as, when the remaining length L of the rolled material currently rolling is the remaining length L _2, to begin deceleration of the rolling speed V, the material being rolled during the deceleration When the roll is released from the roll, start changing the rolling position of the roll,
Switching is performed continuously to the deceleration.

Specifically, first, the current rolling-down position is detected by a speed detector of the rolling-down motor or the like, and the amount of change in the rolling-down position is calculated from the detected value of the current rolling-down position and the set value of the rolling-down position of the next pass. x [mm] is calculated, and the reduction position change amount x
From time to time of rolling positioning completion time (rolling APC completion time) t _s
Is obtained from the following equation (1) (see FIG. 2). (1-
1) has a large pressing position change amount x, if it can ensure the intermediate transfer acceleration and deceleration movement and maximum speed v ₁₀ of pressure (Fig. 1
Equations (1-2) and (1-2) are for the case where the reduction position change amount x is small and only the acceleration / deceleration movement for the reduction is performed (see FIG. 1 (b)).

[0010]

(Equation 1)

Meanwhile, as shown in FIG. 2, time T _B of the reference velocity V _B in the rolling speed V reference speed -V _B (reverse path) from (primary path) is, T _B = 2 · V _B / beta (Β: Acceleration / deceleration rate of rolling [m / s ² ]) Therefore, T _B is compared with t _s of the equation (1), and when T _B ≦ t _s1 , _{ts 2} , the return is made. since there is a margin, as shown in FIG. 1 (a), release chewing slab at the reference speed V _B from the work roll after forward deceleration causes bitten to the work rolls at the reference speed -V _B after reverse acceleration, in the case of T _B> t _s1, t _s2, since reduction APC completion time is short, as shown in FIG. 1 (b), the slabs at the reference speed V _B following rates after forward deceleration from the work roll and release chewing causes bitten to the work rolls at the reference speed -V _B following speed after reversing acceleration.

This case will be described in more detail.
For, as shown in FIG. 3 (a), because there is room in crosscut, [- i] First, to decelerate the rotation of the work roll as the rolling speed V at the time of release chewing becomes the reference velocity V _B. For this purpose, the rolling length is obtained by a higher-level computer (process computer), and the remaining length is calculated based on the rolling length (the current roll length is obtained from the rotation amount of the work roll rotation drive motor from biting). calculating a, the current determines the difference of the rolling length and rolled cast length) is performed, the remaining length starts decelerating when it becomes L ₁ satisfying the following equation (2), beta
Stop at a stretch at the deceleration rate.

[0013]

(Equation 2)

[ _-B ] Next, the timing of the turning back is determined so that the meshing is performed at the reference speed -VB when the reduction APC is completed. Time T _1B required to accelerate to the reference speed -V _B, since a V _B / beta, remaining length x ₁ of the pressure APC may be determined to complete x ₁ at V _B / beta. At this time, two cases can be considered as shown in FIG. 3 (b), depending on the difference in the magnitude of the acceleration / deceleration rate α under rolling. The Figure 3 when the A in (b) (when α is large) may be determined to the remaining length x ₁ satisfies the following equation (3-1). In the case of B in FIG. 3B (when α is small), from v ₀ that satisfies the following equation (3-2), the remaining length x _{1 of the} equation (3-3) (= １ ／ · α)・ (V _B / β)
² ) can be obtained.

[0015]

(Equation 3)

Next, the case of, as shown in FIG. 4, it is necessary to match the slabs crosscut time T ₂ and pressure APC completion time t _s2. Therefore, in this case, the reference speed V
_It releases the bite at a lower speed than _B and immediately switches back. In the rolling process at this time, assuming that the amount of change in the rolling position is x, x = (v ₁₀ ′) ² / α, the maximum speed v ₁₀ ′ is obtained, and the rolling APC completion time t
_s2 is t _s2 = 2 · (x / α) ^1/2 . Here, since the time from the release of the bite to the return and the return to the bite is the same time, t _s2 / 2 = (x / α) ^1/2 , and the above [−
Similar to Lee], by the remaining length calculation of L ₂ using the following equation (4) can determine the timing of start of deceleration.
The timing of the crosscut are no particular, after decelerated by the deceleration timing L _2, by directly Kirikaesu, APC
The time of completion and the time of biting can be matched.

[0017]

(Equation 4)

As described above, at the time when the rolling pass completion time of the next pass is calculated, the target timing of the start of deceleration and the turning back is determined. Based on this, the deceleration is started before the rolled material is released from the roll. When the roll is released, the roll position is changed, and the rollback is performed so that the timing of the completion of the roll positioning and the timing of the next pass coincide with each other. The time required for turning back is greatly reduced, and productivity is improved.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on an embodiment shown in the drawings. This is an example applied to hot rolling of a thick plate by a quadruple reversible rolling mill. 5 and 6
FIG. 1 shows a block diagram of a control device for implementing the rolling method of the present invention, and a flowchart of the rolling method. FIG.
2 shows a graph of the rolling positioning timing and the change of the rolling speed in the present invention and the conventional control device. FIG. 8 shows a graph comparing the results of the rolling control between the present invention and the related art.

In FIG. 5, the configuration of the device of the present invention is the same as the configuration of the device for performing the conventional automatic switching operation.
A pair of upper and lower work rolls 1 and 2 of the quadruple reversible rolling mill are each rotationally driven by a rotary drive motor 5, and the speed of the rotary drive motor 5 is controlled by a motor drive device (thyristor) 8. In addition, a speed detector (pulse generator) 9 is coaxially installed in the rotary drive motor 5 to detect the actual speed of the rotary drive motor 5.

The upper work roll 1 and the upper backup roll 3 are driven by a screw-down screw system using a screw-down motor 6.
Fixed lower work roll 2 and lower backup roll 4
, And the speed of the screw-down motor 6 is controlled by a motor drive device (thyristor) 10. In addition, a speed detector 11 is provided on a rotary drive gear or the like of the screw-down motor 6 and detects the screw-down position of the upper work roll 1 and the upper backup roll 3. Further, a load cell (load cell) 12 is provided between the rolling device and the roll, and a rolling load (roll load) is detected.

Speed detector 9, speed detector 11, load meter 1
2 is output to the control device (PLC: programmable controller) 13. In the control device 13, the rotational drive motor 5 is controlled based on the set value from the host computer (process computer) 14 and the detection signal.
In addition, the automatic switching operation is performed by controlling the pressure reduction motor 6.

In such a configuration, according to the present invention, the processing program in the conventional control device 13 is changed, and the control device 13 in which the new processing program is stored is used.
The following shortest time rolling control is performed (see the flowchart of FIG. 6). Note that the above-described equations (1) to (4) are set in the new processing program.

(1) Biting detection With the rolling amount set based on the rolling schedule of the process computer 14, the upper and lower work rolls 1 and 2 are driven to rotate, and rolling is started. When the leading end of the slab 7 bites into the upper and lower work rolls 1 and 2, the roll load fluctuation is detected by the load meter 12, and the next roll-down positioning completion time is calculated based on the bite detection signal.

(2) Calculation of Rolling Position Completion Time The rolling position change amount x [mm] based on the current rolling position detection value from the speed detector 11 and the next path rolling position setting value from the process computer 14. Is calculated, and the rolling positioning completion time t _s is obtained from the above-described equation (1) from the rolling position change amount x. As shown in FIG. 2, time T _B of the reference velocity V _B of the rolling speed V (primary path) from the reference velocity -V _B (reverse path), the reduction positioning completion time t _s
In the case of T _B ≦ t _s1 , t _s2 , since there is a margin for switching back, the control shown in FIG. 3 is performed, and T _B > t _s1 ,
In the case of t _s2, the control shown in FIG. 4 is performed because the rolling positioning completion time is short.

(3-1) Control of FIG. 3 The remaining length L of the slab being rolled is calculated from the current pressure extension from the speed detector 9 and the rolling length from the process computer 14, and the remaining length L is calculated. The length L is L obtained from equation (2).
_When it is equal to 1, deceleration of the upper and lower work rolls 1 and 2 is started and stopped at a stretch at a deceleration rate of β. Although the slab is released biting from the upper and lower work rolls 1 and 2 at the reference speed V _B,
This biting is detected by a change in the roll load of the load meter 12, and the pressing-down positioning of the screw-down device is started by the biting detection signal. When the reduction rate α under rolling is large,
Seeking remaining length x ₁ which can accelerate to the reference speed -V _B using equation (3-1), performs crosscut at the timing of the remaining length x _1. If the deceleration rate of the pressure α is small, the crosscut in (3-2) determine the v ₀ with equation performs crosscut at the timing of this v _0, or v timing of the remaining length x ₁ obtained from ₀ Do.

[0027] By performing the crosscut as described above, the timing bite at reference velocity V _B that do not insufficient torque, the timing of the reduction position complete match.

(3-2) Control of FIG. 4 The remaining length of the slab being rolled is calculated from the current pressure extension from the speed detector 9 and the rolling extension from the process computer 14, and this remaining length is calculated. When There (4) matches the L ₂ obtained from the equation starts deceleration of the upper and lower work rolls 1 and 2,
Deceleration and reverse switching are performed at the deceleration rate of β. Slab is released chew from the upper and lower work rolls 1 and 2 below the reference speed V _B, after being continuously made crosscut, biting down work rolls 1 and 2 below the reference speed V _B that do not insufficient torque, the chewing And the timing of the completion of the pressing down position coincidence.

<Numerical example> Rolling schedule Slab size: thickness 250 x width 1579 x length 2418
[Mm]-Rolling size: thickness 6.98 x width 2746 x length 4918
9 [mm] · Heating furnace extraction temperature: 1115 ° C · Reduction amount setting: 0.89 to 18.02 [mm] · Acceleration / deceleration rate under electric reduction: α = 30 [mm / s ² ] · Speed during electric reduction : V ₁₀ = 30 [mm / s] ・ Acceleration / deceleration rate of rolling: β = 2.6 [m / s ² ] ・ Rolling speed: V _T = 5.2 [m / s], V _B = 2.6
[M / s] Under the above conditions, the rolling position change amount x ≦ 18.02 m
m, x <v ₁₀ ² / α in the above equation (1)
(= 30mm), the rolling positioning completion time t
_s2 is given by t _s2 = 2 · (x /
α) ^1/2 ≦ 1.55 seconds. On the other hand, time T _B of the reference velocity V _B to the reference speed -V _{B is, T B = 2 · V B} / β =
Since it is 2 seconds and T _B > _{ts 2} is satisfied, the control of FIG. 4 is performed. Assuming that V _T = 5.2 m / s, L ₂ =
1/2 (V _T ² /β-(β/α)·x)=4.42 m
(In the case of x = 18.02 mm), and the deceleration is started when the remaining length of the material to be rolled becomes 4.42 m.

As described above, the rolling positioning completion time t _s2
Is a short time of 1.55 seconds, so that the slab has the reference speed V
_B is releasing chewing below, but will be caught below the reference speed V _B, for simplicity, when the biting release-biting at the reference speed V _B is made, as shown in FIG. 8, within 2 seconds Thus, the rolling positioning is completed. In the conventional case, it takes about 4.5 seconds to switch back, and in the present invention, the time can be reduced by 1.5 seconds on the basis of the start of deceleration at each turnback of each path, and the switching time is set to 2.
The time can be reduced by about 5 seconds.

As shown in FIG. 7, according to the present invention, in both cases where the amount of change in the rolling position is large and when the amount of change in the rolling position is small, the switching time can be shortened as compared with the conventional case. Particularly, the effect is remarkable. Normal,
In a rolling mill for a thick plate, there are about 10 passes / slab, so assuming that the shortening time is 1 second / pass, the reduction is 10 seconds / slab. This means that if the production capacity is 4000T /
D, when applied to a slab single weight 20T / sheet mill, about 10
The production capacity is improved by 0 T / D (2.5%), which greatly contributes to the improvement of productivity.

In the above description, the case where the rolling position is determined for each pass in the hot rolling of a thick plate has been described. However, the present invention is not limited to this, and processing such as positioning is performed for each pass in other reversible rolling. The present invention can be applied to such cases.

[0033]

As described above, according to the present invention, in a reverse mill in which the rolling position of the roll is changed for each pass and the rollback is performed in several passes, the rolling of the material being rolled before rolling is started before the roll is released. The deceleration of the speed V is started, and the change of the roll reduction position is started at the time when the roll of the rolled material is released during the deceleration, and the roll reduction positioning completion timing coincides with the roll engagement timing of the rolled material in the next pass. Since the material to be rolled is turned back as described above, the following effects can be obtained.

(1) The time required for turning the rolled material from roll release to roll engagement can be greatly reduced as compared with the conventional automatic switching operation, and the production efficiency can be greatly improved. .

(2) Since it is only necessary to change the processing program without changing the device configuration, the object can be achieved easily and inexpensively.

[Brief description of the drawings]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a graph of rolling speed change and rolling positioning timing showing a shortest time rolling method of the present invention, wherein (a) shows a case where there is a margin in a rolling positioning time, and (b) shows a case where a rolling positioning time is short. Is shown.

FIG. 2 is a graph showing the relationship between the rolling positioning time and the time from a normal rotation reference time to a reverse rotation reference time in the present invention.

FIG. 3 shows the timing of deceleration start and return when there is a margin in the rolling positioning time in the present invention,
(a) is a graph showing a change in rolling speed and a timing for reducing the rolling position.

FIG. 4 is a graph of a change in rolling speed and a timing of a rolling positioning showing a timing of a start of deceleration and a timing of a return when a rolling positioning time is short in the present invention.

FIG. 5 is a control block diagram for implementing the shortest time rolling method of the present invention.

FIG. 6 is a flowchart of the shortest time rolling method of the present invention.

FIGS. 7A and 7B are graphs comparing the rolling speed change and the rolling positioning timing between the conventional and the present invention, wherein FIG. 7A shows the conventional case, and FIGS. 7B and 7C show the present invention.

FIG. 8 is a graph comparing the results of the rolling control between the present invention and the related art.

FIG. 9 (a) is a schematic side view showing a configuration of a quadruple reversible rolling mill, and FIG. 9 (b) is a schematic side view sequentially showing a conventional automatic turning operation.

FIG. 10 is a graph showing a change in a rolling speed and a timing of a reduction positioning in a conventional automatic turning operation.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Upper work roll 2 ... Lower work roll 3 ... Upper backup roll 4 ... Lower backup roll 5 ... Rotation drive motor 6 ... Press-down motor 7 ... Slab 8 ... Rotation drive motor drive device 9 ... Rotation drive motor speed detector 10 ... Step-down motor drive unit 11 ... Step-down motor speed detector 12 ... Load cell 13 ... Control unit 14 ... Host computer

Claims (3)

[Claims] 1. In a reverse mill in which roll rolling position is changed for each pass and return rolling of several passes is performed, a reduction in a rolling speed V is started before a roll to be rolled of a material being rolled is released. At the time when the rolled material of the rolled material is released from the roll during the deceleration, the change of the roll reduction position is started, and the rolled-back material is turned back so that the roll reduction positioning completion timing and the roll engagement timing of the rolled material in the next pass coincide. A shortest time rolling method for a reverse mill, which is performed. 2. In a reverse mill in which the roll rolling position is changed for each pass and roll pass rolling is performed in several passes, the roll rolling position is changed from the roll rolling position change amount x from the current rolling position of the roll to the rolling position of the next pass. completion time seeking t _s, in this case reduction positioning completion time t _s is greater than a predetermined value, the remaining length of the rolled material as the rolling speed V during release chewing roll the material to be rolled becomes around reference speed V _B L Calculate ₁ and
When the remaining length L of the rolled material currently rolling is the remaining length L _1, rolling speed starts to decelerate and V, the roles of the pressing position at the time the material to be rolled is released chew from the roll during the deceleration The reverse mill is characterized in that the change is started, and then the rolled material is stopped, and then the rolled material is turned back so that the roll reduction positioning completion timing and the biting timing of the rolled material in the next pass match. The shortest time rolling method. 3. In a reverse mill in which rolling reduction of a roll is changed for each pass and return rolling of several passes is performed, rolling reduction is performed by a reduction amount x of a rolling reduction from a current rolling position of a roll to a rolling reduction of a next pass. completion time seeking t _s, if the pressure positioning completion time t _s is less than the predetermined value, the remaining length of the rolled material, such as timing biting of the material to be rolled in the roll reduction positioning completion timing and the next path matches L _When the remaining length L of the material to be rolled currently being rolled reaches the remaining length L ₂ , the rolling speed V starts to be reduced, and at the time when the material to be rolled is released from the roll during this reduction. A short-time rolling method for a reverse mill, characterized by starting to change a rolling position of a roll and performing a turn back continuously to the deceleration.