JP3205134B2 - Anti-slip rolling method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control method for controlling a hot rolling mill so as to prevent slippage during rolling and to automatically avoid slippage when a slippage occurs.

[0002]

2. Description of the Related Art The slip phenomenon during rolling in a continuous hot rolling mill occurs frequently in a rough rolling mill requiring a large rolling reduction.

[0003] It is known that slip during rolling largely depends on the state of the draft and the surface roughness of a rolling work roll. In other words, while the surface roughness of the roll surface is small, such as immediately after the roll change, or during the process in which the rolling has progressed considerably after the roll change, the roll skin surface changes to a mirror surface state (referred to as black scale formation). ), The surface roughness of the roll surface becomes extremely small and slip occurs.

[0004] When slippage is likely to occur as described above, it is common practice to reduce the rolling speed or reduce the rolling reduction in order to prevent slippage during rolling. I have.

[0005]

However, it is difficult to quantitatively recognize the continuously changing surface condition of the roll surface during the rolling operation, and even if the surface condition of the roll surface can be grasped, it is difficult to recognize the required reduction amount. Since it is not known how much the rolling speed can be avoided on the roll surface skin in the state, it is actually operated at a considerably safe side rolling speed and rolling reduction considering the change in the roll surface during rolling. In general, the rolling mill is not able to fully exercise its rolling capacity. In general, when setting the rolling speed, the amount of reduction required by the mill (in the case of multiple-pass rolling, the reduction per pass) Is calculated by the following equation.

[0006]

(Equation 1)

In order to determine the rolling speed at which the rolling angle can be rolled without causing a slip at the biting angle θ, the rolling speed is variously changed and the rolling speed is determined by trial and error, and the limit rolling speed corresponding to the biting angle θ is obtained. Rolling is performed at that speed.

However, despite rolling at such a limit rolling speed and taking measures to prevent slippage,
A slip may occur due to a change in the roll skin surface or the like. In such a case, the operator performs a slip avoidance operation such as reducing the rolling speed or reducing the rolling reduction.

However, since there is no index for judging at which rolling speed the amount of deceleration operation can be avoided and whether or not the slip is in a danger zone, as a result, the slip state can be avoided by considerable overaction. In many cases, the operation is continued where it is located.

[0010]

In order to solve the above-mentioned problems, the present invention measures the speed of a material to be rolled at the exit side of a rolling mill during rolling using a sheet speed meter installed at the exit side of a hot rolling mill. And
Continuously calculate the actual advance rate obtained from the measured rolling material speed and the rolling mill roll peripheral speed, compare the actual advance rate obtained with the lower limit advanced rate of the stable rolling state, and the actual advance rate is When it is smaller than the lower limit advanced rate, the rolling speed is reduced corresponding to the deviation.

Then, the actual advanced rate becomes smaller than the lower advanced rate, the rolling speed is reduced in accordance with the deviation thereof, and then the actual advanced rate is calculated again. Is compared with the lower limit advanced rate, and if the actual advanced rate is smaller than the lower limit advanced rate, the rolling mill is controlled in a direction in which the rolling reduction is reduced.

[0012]

The present invention focuses on the fact that the correlation between the actual advance rate of the material and the tendency to slip is very high when slip occurs or when the surface of the roll skin surface is so small that slip is likely to occur ( It is intended to automatically avoid slip during rolling based on the actual advance rate. Thereby, the conventional disadvantages can be avoided.

[0013] Looking at the actual advance rate during rolling from a roll change to the next roll change in time series, it can be roughly classified into two patterns as shown in FIG. One is the case where the advance rate is small and slip is likely to occur in the initial rolling stage immediately after the roll change, the roll surface becomes rough with the progress of rolling, the advanced rate gradually increases, and there is no slip and it is stable (Case 1). The other is the case in which black scale is gradually formed on the roll skin as the rolling progresses after recombining, the black scale grows into a mirror-like state, the advance rate decreases, and slip tends to occur. 2).

In either case, when the actual advanced rate becomes smaller than a predetermined value (φ _F = 0.3), slip occurs almost certainly during rolling, and when it becomes close to the predetermined value, the width and reduction of the rolled material decrease. It has been confirmed through actual rolling that a state in which slip is likely to occur due to a slight change in an element such as the amount, that is, a slip danger zone is obtained.

Focusing on such knowledge, the present invention is to continuously measure the advance rate of the material being rolled, and to avoid slipping when the rolled material is in a danger zone of slip from the obtained actual advance rate. Is automatically performed.

[0016]

FIG. 3 shows the configuration of a main part of a rolling mill including a slip prevention control device according to an embodiment. In FIG. 3, 1 is a rolled work roll, 2 is a work roll drive motor, 3 is a reduction device, 4 is a reduction motor, 5 is a laser plate speedometer,
6 is a work roll rotation detector, 7 is a roll peripheral speed calculator ,
9 is a slip prevention output calculator, 10 is a rolling speed correction calculator, 11 is a rolling speed control device, 12 is a rolling reduction calculator,
13 is a rolling control device, 14 is a rolled material, 15 is a conveying table roller, 16 is a table speed detector, and 17 is a slip alarm device.

The rolling material speed V _FS on the exit side of the rolling mill is
Is continuously measured by the laser plate speedometer 5 installed on the output side (the rear surface during odd-pass rolling, the front surface during even-pass rolling),
The work roll rotation speed is detected by a work roll rotation detector 6. Roll peripheral speed calculator 7, the rolling mill b from the detected work roll rotational speed and the work roll diameter D _R - calculating the Le peripheral velocity V _MS, forward slip calculator 8, and was measured rolled material speed V _FS , rolling mill roll peripheral speed calculator 7 is calculated b - calculating a continuous actual forward slip phi _F Le peripheral velocity V _MS.

[0018] _{φ F = V FS / V MS} V MS = π × D R × N D R: work roll diameter N: B - Le rotational speed (rotational speed) slip output calculation unit 9, the actual advanced input Rate φ
Comparing the _F reference forward slip of the slip limit corresponding (lower forward slip) and phi _B, if actual forward slip <reference forward slip phi _B, corresponding to the forward slip deviation phi _D shown below, to slow the rolling speed For this purpose, a speed correction deceleration signal △ N is output.

Advanced rate deviation amount φ _D = reference advanced rate φ _B −actual advanced rate φ _{F In} this example, ΔN proportional to φ _D is generated, but a proportional / integral operation used in general control is performed. it is also an effective means for generating a speed correction signal (△ N) based on a result of processing the forward slip deviation phi _D by.

Since the target rolling speed input to the rolling speed control device 11 is reduced by the speed correction deceleration signal △ N, the rolling speed is reduced, and usually, the actual advanced rate is restored to the reference advanced rate level, and the advanced rate is reduced. The deviation amount is within the allowable value, and the occurrence of slip is avoided.

If the advance rate deviation does not become less than the allowable value even if the rolling speed reaches a predetermined lower limit speed by speed correction (deceleration), the slip prevention output calculator 9 sets the rolling speed lower than the lower limit speed. The update of the rolling speed is stopped so that the rolling reduction is not performed, and the rolling reduction correction signal ΔS is output instead.
Slip is avoided by reducing the amount of reduction.

FIG. 4 shows a processing flow of the above-described slip prevention control system. This will be described with reference to FIG. Carry out speed correction, if the advanced rate deviation does not recover to within the allowable value even if the rolling speed is the lower limit of the predetermined speed, it is preferable from the viewpoint of temperature drop etc. Therefore, the slip avoidance control (deceleration) output by the speed correction is stopped when the rolling speed reaches the predetermined lower limit speed.

When the deviation of the advanced ratio does not become less than the predetermined amount even when the rolling speed reaches the predetermined lower limit speed, the slip avoidance operation can be performed by continuously reducing the rolling reduction corresponding to the deviation amount similarly to the rolling speed. When the actual advanced rate recovers to the reference advanced rate level, the deviation becomes zero and slip avoidance is performed.

In order to avoid slippage by reducing the rolling reduction, the required rolling reduction in the rolling pass cannot be ensured. Therefore, the rolling reduction in the remaining rolling pass on the rolling schedule or the rolling reduction at the subsequent stage can absorb the insufficient rolling reduction. The correction is performed in the range up to the correction upper limit.

If the slip ratio is not recovered even after performing the slip avoidance correction control based on the rolling speed correction and the reduction amount correction, the actual rolling material speed V _FS measured by the sheet speed meter and the output side plate are compared. The slip is detected based on the deviation of the table roller speed _VTR rotating in synchronization with the speed. When the deviation exceeds a predetermined amount, the alarm setting unit 17 issues a warning of occurrence of a slip, and notifies the operator that measures such as changing the rolling schedule or changing the roll are necessary because the slip control range has been exceeded. I do.

[0026] In this embodiment, based on the accumulation of actual operation data in the proper roll skin surface, using the following equation showing the relationship between the biting angle θ and limits the rolling speed V _R, the reference and and determines the composed rolling speed V _R.

[0027]

(Equation 2)

FIG. 5A shows the result of setting the speed of each rolled material from the bite angle of the rolled material based on the above equation.
FIG. 5B shows the change in the actual advance rate at this time. From the viewpoint Although the allowable amount of the slip during rolling in accordance with the magnitude of the reference forward slip phi _B is determined, in this example, to the utmost avoid inhibition of productivity due to accompanying rolling speed drops slip prevention control, the reference forward slip phi _B are defined in 0.03 is a boundary point between the slip Critical and slip generation area shown in FIG. The allowable value shown in FIG. 4 is set to 0.01.

Referring to FIG. 5, since the slip avoidance control is initially OFF, the advance rate gradually approaches the danger area of slip with a decrease in the roll skin surface roughness. Since the speed correction works, it can be seen that the actual advanced rate rises and returns to the reference advanced rate, and the sporadic slips before that are avoided by the appropriate speed correction amount.

[0030]

In the prior art, the rolling speed itself set at a low level in order to avoid a threading trouble due to the occurrence of a slip, and an appropriate operation cannot be taken once a slip has occurred. Means such as a significant reduction in rolling speed at the expense of productivity or an earlier roll change must be taken. However, even if the slip reaches the danger zone by applying the present invention, a stable rolling speed (speed It is possible to operate at the (up) level, which greatly contributes to improvement of productivity and stable operation of the rolling line.

[Brief description of the drawings]

FIG. 1 is a graph showing the relationship between the actual advance rate and the danger area / occurrence area of slip.

FIG. 2 is a graph showing a transition of an actual advanced rate after a role change, wherein Case 1 shows a case without black scale, and Case 2 shows a case with black scale generation.

FIG. 3 is a block diagram illustrating a main part of a rolling device according to an embodiment.

FIG. 4 is a flowchart showing processing of a slip prevention control system.

FIG. 5 is a graph showing changes in the rolling speed and the actual advance rate in the apparatus of the example.

[Explanation of symbols]

1: Rolling work roll 2: Work roll drive motor 3: Roll-down device 4: Roll-down motor 5: Laser plate speedometer 6: Work roll rotation detector 7: Roll peripheral speed calculator 8: Advanced rate calculator 9: Slip prevention output Computing unit 10: Rolling speed correction computing unit 11: Rolling speed control unit 12: Rolling down correction computing unit 13: Rolling down control unit 14: Rolled material 15: Transport table roller 16: Table speed detector 17: Slip alarm device

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-4-59113 (JP, A) JP-A-58-192614 (JP, A) JP-A-59-24504 (JP, A) JP-A-60-1985 44103 (JP, A) JP-A-5-212422 (JP, A) JP-A-59-147704 (JP, A) JP-B 5-20173 (JP, B2) JP-B-57-18962 (JP, B2) (58) Field surveyed (Int. Cl. ⁷ , DB name) B21B 37/46 B21B 37/00

Claims (2)

(57) [Claims] 1. A plate speedometer installed on the outlet side of a hot rolling mill
The rolling material speed on the exit side of the rolling mill during rolling.
Determined from the specified rolling material speed and rolling mill roll peripheral speed
The calculated achievement rate is calculated continuously, and the achievement achievement obtained
Rate compared with the lower limit advanced rate in the stable rolling state,
When the rate becomes smaller than the lower limit advanced rate, their deviation
Correspondingly, reduce rolling speedAnd After this deceleration, the actual advance rate is calculated again, and the latest
Compare the actual advanced rate to the lower advanced rate
If the rolling rate is smaller than the advance rate, the rolling mill
Control,  An anti-slip rolling method, characterized in that: 2. The method according to claim 1, wherein the reduction of the rolling speed and the reduction of the rolling reduction are performed.
Even if it does, the advanced rate of achievement does not recover and it is in a rolling slip state
If the, and actual rolled material speed V _FS by the plate speedometer,
The speed of the table roller rotating in synchronization with the speed of the exit plate
Detecting a slip by deviation of V _TR, the difference is a predetermined amount
2. An anti-slip rolling method according to claim 1 , wherein an alarm is generated when the value exceeds the limit.