JPH0771684B2 - Method of preventing thickness variation due to roll eccentricity - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for preventing plate thickness fluctuation due to roll eccentricity in a rolling mill, and in particular, it can be realized at a low cost by an extremely simple means and has a relatively long length. The present invention relates to a method for preventing plate thickness variation due to roll eccentricity, which is also suitable for irreversible rolling of long rolled materials and high speed rolling.

[Conventional technology]

Conventionally, as a method for preventing the plate thickness variation due to roll eccentricity in a rolled material, for example, the amount of roll gap change due to roll eccentricity is calculated, and the plate thickness is changed by operating the reduction device to cancel it. Control (Japanese Patent Application Laid-Open No. 64-87010), or the positional relationship between the upper and lower backup rolls, which shows the minimum roll load variation during kiss roll drive, is detected and stored in advance, and Techniques such as controlling the rotational speed of the work rolls (Japanese Patent Publication No. 62-19241) have been provided so as to make the positional relationship between the upper and lower backup rolls equal to the stored positional relationship between the upper and lower backup rolls.

[Problems to be Solved by the Invention]

However, in the former case of the above conventional method,
The rolling pressure and strip thickness signals are actually affected by various factors such as rolling force, hardness of rolled material, rolling speed, etc. other than backup roll eccentricity, so it is difficult to determine the roll gap change due to roll eccentricity. There was a drawback that a satisfactory correction effect could not be expected, and in particular during high-speed rolling, the hydraulic rolling-down device was delayed in tracking and accurate correction / control could not be performed.

Also, in the latter type that controls the rotation of the work roll during operation, since the work roll is in direct contact with the material to be rolled, slippage occurs between the work roll and the rolled material, albeit somewhat. In addition to the risk of scratches on the surface of the rolled material and the work rolls, there is a disadvantage that it can be applied only to an independently driven rolling mill in which the upper and lower work rolls are driven by independent drive sources.

Furthermore, both of them control the drive system of the rolling down device or the roll during operation, so that each device to be controlled requires high-speed and high-accuracy responsiveness as well as mechanical mechanism. However, there are drawbacks in that it is complicated and extremely expensive, and it is difficult to adjust and easily causes a failure.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method capable of effectively suppressing a plate thickness variation due to eccentricity of a roll by an extremely simple means.

[Means for Solving the Problems]

The method for preventing plate thickness variation due to roll eccentricity according to the present invention is a rolling mill in which upper and lower work rolls are synchronously driven, in advance, the outer diameters of the upper and lower backup rolls are within a required minute range in which the outer diameter difference between both backup rolls is required. In addition to setting it to be included, the kiss roll operation is performed in each phase state while changing the relative phase in the rotation direction of both backup rolls by idling at least one of the upper and lower backup rolls with respect to the other roll. The relative phase of the upper and lower backup rolls that minimizes load fluctuation due to eccentricity is detected and stored, and at least one of the upper and lower backup rolls is idled with respect to the other before rolling starts. Combine the phases at the target position and then start rolling. It is an feature.

[Action]

By minimizing the difference in diameter between the upper and lower backup rolls, it is possible to make the waviness of the plate thickness fluctuation caused by the eccentricity of the upper and lower backup rolls long (long wavelength). On the other hand, even if the upper and lower backup rolls have eccentricity, the variation of the plate thickness is small at the point where they are in a phase of canceling each other's eccentricity.

Therefore, by satisfying the above two conditions in an overlapping manner, it is possible to perform long rolling without causing plate thickness variation due to roll eccentricity.

The optimum combination position (optimal relative phase) between the upper and lower backup rolls can be found from the load fluctuation due to the kiss roll operation.

〔Example〕

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

FIGS. 1 and 2 schematically show a rolling mill according to the present invention. In the drawings, reference numeral 1a is an upper work roll, 1b is a lower work roll, 2a is an upper backup roll, and 2b is a lower backup roll. is there. In this case, this rolling mill is of a vertical synchronous drive system in which the upper work roll 1a and the lower work roll 1b are driven by a common drive source (motor or the like) 3. Below the lower backup roll 2b, a hydraulic pressure reduction cylinder 4 with a reduction direction position detector is provided, and above the upper backup roll 2a, a rolling load detector (load cell) 5 is provided. Upper and lower work rolls 1a, 1b
Are separated by a work roll balance cylinder 6 interposed therebetween, and the upper backup roll 2a and the upper work roll 1a are separated by an upper backup roll balance cylinder 7 interposed therebetween.

Further, the upper and lower backup rolls 2a, 2b are set so that the outer diameter difference (pair difference) between them is extremely small. For example, the error of the outer diameters of these two backup rolls 2a, 2b Is set to be within 0.008%. The pair difference between the work rolls 1a and 1b is originally set within a very small range.

FIG. 3 shows a configuration example of a control mechanism and a control circuit attached to the rolling mill to realize the present invention.

In the figure, reference numeral 8 is an upper backup roll that detects the position in the rotational direction of the upper backup roll 2a, that is, the number of rotations of the upper backup roll 2a rotating around the axis from the reference position (phase from the reference position). Similarly, reference numeral 9 is a lower backup roll rotational position detector for detecting the position of the lower backup roll 2b in the rotational direction. The upper backup roll rotational position detector 8 and the lower backup roll rotational position detector 9 determine the initial values of the rotational positions of the upper and lower backup rolls 2a and 2b based on the signals from the both rotational position detectors 8 and 9. It is connected to an initial relative phase memory device 10 for storing. Further, the initial relative phase memory device 10 is
10 and a relative phase change command device 11, which is connected to an adder circuit 12 that performs an operation based on signals from the adder circuit 12
Is connected to the determination circuit 13, and the determination circuit 13 is connected to the drive source control device 14. Then, the control device 14 causes the drive source 3 to
The drive source 3 is connected to the drive source control device.
It is designed to be controlled based on 14. Also,
Either one of the upper backup roll rotation position detector 8 or the lower backup roll rotation position detector 9 (the lower backup roll rotation position detector 9 in the illustrated example) is also connected to the determination circuit 13. Judgment circuit 13
Is a signal from the one rotational position detector 9 and an adding circuit.
The determination result based on the signal from 12 is sent to the control device 14. Further, the signal from the rolling load detector 5 is connected via a signal averaging processor 15 to a storage table 16 which stores a load fluctuation value corresponding to the relative phase of the upper and lower backup rolls 2a and 2b.

Next, based on the above configuration, a plate thickness variation preventing method due to roll eccentricity according to the present invention will be described.

First, in order to facilitate understanding of the present invention, FIG. 4 is a flowchart showing a rough work procedure for carrying out the present invention.

That is, after setting the upper and lower backup rolls 2a and 2b in SP (step) -A so that the dimensional difference (pair difference) between their outer diameters is within a required minute range, in SP-B, the The phase of the upper and lower backup rolls 2a and ab at which the load fluctuation during rolling of the kiss rolls, which is read by the rolling load detector 5, is minimized is found, and rolling is performed in SP-C in accordance with the phase.

FIG. 5 details the contents of SP-B in FIG. That is, in order to detect the phase of the upper and lower backup rolls 2a and 2b in which the load fluctuation is minimized, the following procedure may be performed.

<SP-B10> First, the load fluctuation under the kiss roll state at the current (arbitrary) phase is measured.

To this end, the upper backup roll rotational position detector 8 and the lower backup roll rotational position detector 9 detect the respective phases of the current upper backup roll 2a and the lower backup roll 2b in the rotating direction, Upper and lower backup rolls 2a, 2b based on the detected value
The relative phase, that is, the relative positional relationship is calculated and stored in the initial relative phase storage device 10.

Next, by operating the hydraulic pressure reduction cylinder 4, the upper and lower work rolls 1a, 1b and the upper and lower backup rolls 2a,
All of 2b are brought into contact with each other as shown in FIG. 6 (a) (kiss roll state) and pressure-bonded by a predetermined amount. After that, the drive source 3 is driven to rotate the upper and lower work rolls 1a and 1b and the upper and lower backup rolls 2a and 2b, and the rolling load detector 5 measures the load fluctuation. The measured load fluctuation value is stored in the storage table 16. The storage table 16 is adapted to record the rolling load fluctuation amount corresponding to the relative phase of the upper and lower backup rolls 2a and 2b as shown in the figure.

<SP-B20> Next, the edge between the upper and lower backup rolls 2a and 2b is cut. To this end, the hydraulic pressure reduction cylinder 4 may be retracted and the upper backup roll cylinder 7 may be extended to obtain the state as shown in FIG. 6 (b).

<SP-B30> When the above state is reached, the lower backup roll 2b is operated by operating the drive source 3 as shown in FIG. 6 (c).
Is rotated to change the relative phase between the upper and lower backup rolls 2a and 2b.

The phase change here is performed by rotating the lower backup roll 2b in the circumferential direction by a constant angle that is equally divided (for example, π / 4 into 8 equal parts).

<SP-B40> After the phase change, each roll is put in the kiss roll state again as shown in FIG. 6 (d).

<SP-B50> By operating the drive source 3, the load fluctuation at the position where the phase is newly changed is measured.

<SP-B60> If the operation of the SP-B50 is less than the specified number of times, that is, 2π for one rotation of the lower backup roll 2b, the above SP-B50 is used.
When the operations from B20 to SP-B50 are repeated and the specified number of times have been executed, the processing advances to SP-B70.

<SP-B70> By the following procedure, the relative phase of the upper and lower backup rolls 2a and 2b that minimizes the load fluctuation by the rolling load detector 5 is found.

As shown in FIG. 7, the lower backup roll 2b is divided into eight equal parts, for example, π / 4, and the points are designated as R ₁ , R ₂ , R ₃ , .... Now here
It is assumed that the positive maximum eccentric point Q ₂ of the actual roll diameter of the lower backup roll 2b exists between the points R ₃ and R ₄ . Then, the measurement result of the load fluctuation is recorded (stored) in the storage table 16 as shown in FIG. 8 by the procedure of the SP-B40 and SP-B50.

FIG. 8 shows that the load fluctuation amount changes (causing “waviness”) due to the relative phase difference between the upper and lower backup rolls 2a and 2b. Here, the graph of the load fluctuation shown in FIG.
The relative positional relationship between the upper and lower backup rolls 2a and 2b shown in (g) is shown correspondingly. The symbols are typically shown only in FIG. In FIG. 9, the black dots added to the upper and lower backup rolls 2a and 2b respectively indicate the plus side maximum eccentric points of the respective backup rolls 2a and 2b. That is, if there is a pair difference between the upper and lower backup rolls 2a and 2b, a phase difference occurs between the two backup rolls 2a and 2b as shown in FIG. 9 due to the rotation. That is, the relationship between the upper and lower backup rolls 2a, 2b having the relative positional relationship shown in FIG. 9 (a) gradually shifts as shown in FIG. 9 (b) → (c) → (d) → ... . And, the fluctuation amplitude of the load is shown in FIG.
In other words, the phase difference between the maximum eccentric points Q ₁ and Q ₂ of both backup rolls 2a and 2b is exactly π (3π,
5π, ...) becomes maximum, and the phase difference between the maximum eccentric points Q ₁ and Q ₂ of both backup rolls 2a and 2b is 0 (2π, 2f).
It becomes the minimum when it becomes 4π,…).

Therefore, one of the backup rolls (the lower backup roll 2b in the embodiment) is equally divided as shown in FIG. 7, and a load fluctuation state corresponding to the relative phase between the upper backup roll 2a and the lower backup roll 2b is set, for example. By recording as shown in FIG. 8, it is possible to find the phase of the upper and lower backup rolls 2a and 2b in which the load fluctuation is minimized.

In this case, the combined relative maximum eccentricity point to Q ₁ upper backup roll 2a, the upper and lower backup rolls 2a so that the interval between the points R _7, R ₈ of the lower backup roll 2b facing the 2b phase, the state If the rolling is performed with, the fluctuation amount of the load becomes the smallest.

As described above, when the optimum relative phase between the upper backup roll 2a and the lower backup roll 2b is found, the upper backup roll 2a and the lower backup roll 2b at that time are found.
The rotational position relative to is detected by the upper backup roll rotational position detector 8 and the lower backup roll rotational position detector 9, and is stored in the initial relative phase storage device 10.

With the above, SP-B in FIG. 4 is completed, and then SP- in FIG.
Move to C.

SP-C is a step of setting the relative phases of the upper and lower backup rolls 2a, 2b to the optimum combined phase detected by SP-B and carrying out rolling, the details of which are shown in FIG.

<SP-C10> If the upper and lower backup rolls 2a and 2b are set to the optimum phase state by the SP-B, the upper and lower backup rolls 2a and 2b are respectively changed to the upper and lower work rolls 1a and 1b as shown in Fig. 1 (a). Abut.

<SP-C20> If the upper and lower backup rolls 2a and 2b are set to have the optimum phases as described above, rolling is started (Fig. 11 (b)).

<SP-C30> When performing the next rolling, move to SP-C40.

<SP-C40> This SP-C40 and the following SP-C50 are processes to correct the relative phase shift between the upper and lower backup rolls 2a and 2b caused by the previous SP-C30, and idle time when rolling is not performed. It will be carried out during.

Here, first, as shown in FIG. 11 (c), the edge between the upper and lower backup rolls 2a and 2b is cut. This operation is the same as SP-B20
Is the same as.

<SP-C50> Next, as shown in FIG. 11 (d), the motor 3 is operated to rotate the lower backup roll 2b (idling).
As a result, the phases of the upper and lower backup rolls 2a and 2b are idly rotated so as to be in the initial state, that is, the optimum state in the SP-B70. Top and bottom backup rolls 2a, 2
Since the relative phase for which b is the optimum combination is already detected and stored in the initial relative phase storage device 10, this operation is
In consideration of the stored optimum phase and the phase at which the deviation has occurred at the present time, it is automatically executed by a command from the relative phase change command device 11.

As a result, the upper and lower backup rolls 2a and 2b are combined and rotated again in the initial optimum relative phase, that is, the relative phase in which the amount of load fluctuation due to roll eccentricity is minimized. Moreover, since the pair difference between the two backup rolls 2a and 2b is extremely small, it is possible to perform the most excellent rolling with a small thickness variation over a long time (long length).

Here, the actual diameter of the upper backup roll 2a will now be described by applying actual numerical values to the above embodiment.
D ₁ is φ1300mm, actual diameter of lower backup roll 2b is D ₂ is φ
It is assumed that it is 1300.03 (pair difference: 0.03 mm ≈ 0.0023%).

When both backup rolls 2a and 2b rotate, a rotation difference (phase difference) occurs between the upper backup roll 2a and the lower backup roll 2b. here,
The rotation number N of the upper backup rolls 2a for starting rotation from a certain phase relationship between the backup rolls 2a and 2b and returning to the same phase relationship again is Therefore, one wave length of the waviness of the load fluctuation, that is, the waviness of the plate thickness fluctuation is the length by which the upper backup roll 2a makes 43333 rotations.

At this time, the rolling length l is l = D ₁ π × N ≈177000 [m] Therefore, the length (wavelength) of one cycle of undulation is about 1770.
It will be 00m.

By the way, now, the rolled material has a thickness of 0.3 mm and an outer diameter of φ1900 mm.
If you try to make a coil, the total coil length is about 8500
m, which is less than 5% of the length of one cycle of swell (see FIG. 12).

That is, as described above, the upper and lower backup rolls 2a, 2b
The difference between the pair is set to a small value, and both backup rolls
If rolling is performed by combining 2a and 2b so that the relative phases cancel each other out of eccentricity, when rolling one coil, the "waviness" of the plate thickness fluctuation is one wavelength within the entire length of one coil. Not only does this appear, but it is also possible to make it extremely small so that the variation in plate thickness due to roll eccentricity can be ignored. By setting the relative phase of the upper and lower backup rolls 2a and 2b to the initial setting position for each coil, it is possible to always perform rolling with extremely small thickness variation due to roll eccentricity.

Moreover, the means is extremely easy because the edge between the upper and lower backup rolls 2a and 2b is cut and one of the upper and lower backup rolls 2a and 2b is simply idled. Furthermore, since a complicated device / mechanism for controlling the rolling down device and the drive device is not required during operation, a reliable effect can be realized at low cost.

In the present invention, it is an essential requirement to minimize the difference in outer diameter between the upper and lower backup rolls 2a and 2b, that is, the pair difference, as described above. Of course, it is ideal that this pair difference does not exist at all, but considering both the effect and the processing cost, the range of the pair difference is 0.008% (for example, roll outer diameter φ1300 m
It is desirable to be within 0.1mm). Within this range, a sufficient effect can be exerted on the normal rolling length, and the size setting (processing) of the backup roll is technically extremely easy.

Further, in the present invention, since it is not necessary to control the reduction device during the rolling operation, it is possible to apply the invention to high-speed rolling, which has conventionally been difficult in terms of followability of the reduction device, without any adverse effects. In addition, since there is no slip between the material to be rolled and the work roll, it can be applied to a vertical synchronous drive type rolling mill, and there is no possibility of impairing product quality or damaging the work roll. Further, the present invention can be applied to even a vertically independent rolling mill by operating the upper and lower work rolls in perfect synchronization.

In the embodiment, the upper and lower backup rolls 2a, 2
Although it has been described that the rolling is started from the optimum phase position of b, in practice, it is desirable to set the optimum phase position so as to come to the middle part of the entire rolling length. This is because the variation in plate thickness over the entire length can be suppressed to a smaller range. And if the rolling length is decided in advance,
Such setting of the upper and lower backup rolls 2a and 2b can be easily performed by changing the set value of the relative phase change command device 11 and the like. Therefore, in the present invention, the initial positional relationship between the upper and lower backup rolls 2a and 2b such that the optimum phase relationship is in the middle of the entire rolling length can also be referred to as the optimum initial position.

Further, in the embodiment, the combined load measuring points of the lower backup roll 2b are set at 8 points (8 divisions by π / 4), but it is of course possible to further divide the divisions to increase the measuring points. In such a case, the optimum relative phase of the upper and lower backup rolls 2a and 2b can be obtained more accurately.

〔The invention's effect〕

As described above, according to the present invention, it is possible to reliably achieve rolling over a long length in a state in which the variation in plate thickness due to roll eccentricity is kept within a very small range by extremely simple means. Moreover, since it is not necessary to control the hydraulic pressure reduction device or the drive system during operation, the complexity and
It does not require an expensive control device, can be easily applied to high-speed rolling, and can reliably achieve the effect of preventing plate thickness variation due to roll eccentricity, and does not slip each roll during operation. Therefore, various excellent effects such as the quality of the product can be ensured and the roll life can be ensured are obtained.

[Brief description of drawings]

1 and 2 show the outline of a rolling mill to which the present invention is applied. FIG. 1 is a side view thereof, FIG. 2 is a front view thereof, and FIG. 3 is a control of the rolling mill according to the present invention. FIG. 4 is a circuit diagram showing the means, FIG. 4 is a flow chart showing a procedure outline of a method for preventing plate thickness variation due to roll eccentricity according to the present invention, FIG. 5 is a flow chart showing a part of the contents of FIG. 4 in detail, and FIG. a)
(D) shows the states of the upper and lower backup rolls corresponding to the blocks of the flowchart shown in FIG. 5, and is a side view schematically showing each roll, FIG. 7 shows the lower backup roll, etc. A side view schematically showing each roll for explaining the division points, FIG. 8 is a diagram showing a state of load fluctuation due to a phase difference between upper and lower backup rolls, and FIGS. 9 (a) to 9 (g) are The combined state of the upper and lower backup rolls is shown in correspondence with FIG. 8 and is a side view schematically showing the rolls. FIG. 10 is a flowchart detailing a part of the contents of FIG. 4, FIG. (A) ~
(D) shows the states of the upper and lower backup rolls corresponding to the blocks of the flow chart shown in FIG. 10. A side view schematically showing each roll, and FIG. 12 explain the operation of the present invention. FIG. 6 is a diagram showing a plate thickness variation state in the present invention. 1a …… Upper work roll, 1b …… Lower work roll, 2a …… Upper backup roll, 2b …… Lower backup roll.

Claims (1)

[Claims] 1. In a rolling mill in which upper and lower work rolls are synchronously driven, the outer diameters of the upper and lower backup rolls are set in advance so that the difference between the outer diameters of the upper and lower backup rolls falls within a required minute range. , By rotating at least one of the upper and lower backup rolls against the other while changing the relative phase in the rotational direction of both backup rolls, the kiss roll operation is performed in each phase state to minimize load fluctuation due to roll eccentricity. The relative phase of the backup roll is detected and stored, and at least one of the upper and lower backup rolls is idled with respect to the other before the start of rolling to combine both backup rolls at a position where the detected relative phase is a target, The thickness variation due to roll eccentricity characterized by starting post-rolling Stop method.