JPS6015012A - Method for controlling speed of reversing mill - Google Patents

Abstract

PURPOSE:To prevent a camber generating at the biting tip-part of a material to be rolled by inputting a computing value of impact-drop correcting quantity at the time of biting the material, to a current controller in a system for controlling the driving of work rolls. CONSTITUTION:A rolling torque required for rolling a material S to be rolled is predictively computed by a rolling-torque arithmetic device 10, and the difference between the impact-drop-quantities of work rolls 1, 1' required for preventing the biting tip of materials from generating camber is also computed by an arithmetic device 11. The difference between impact-drop quantities capable of preventing the generation of camber is compared with predictively computed value of the difference between the impact drop quantities of the work rolls 1, 1' at the time of normal rolling to compute the correcting quantity, capable of making both values equal to each other by an impact-drop correcting-quantity arithmetic device 12, thereby inputting correcting signals to current controllers 6, 6' through respective function generators 13, 13'.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a speed control method for a reversing rolling mill that prevents the occurrence of warping of the biting tip of a rolled material when the rolled material is bited into the reversing rolling mill. It is.

When rolling materials such as slabs using a large twin-drive reversible rolling mill such as a plate rolling mill, temperature differences between the upper and lower surfaces of the material to be rolled during the heating process, conveyance process, roll coolant water injection, etc. roll characteristics such as differences in surface roughness, hardness, and diameter of the work rolls, differences in moment of inertia between the upper and lower work rolls due to differences in spindle length between the upper and lower work rolls, and load sharing between the upper and lower work rolls. As shown in FIG. 1, due to various causes such as unbalance between the upper and lower work rolls 1.
If there is a difference in the biting end torque of f, the upper and lower work rolls 1. There is a difference in the impact drop amount of f, which may cause a curve with a radius of curvature ρ to occur at the tip of the rolled material S.

This upper and lower work roll 1. The impact dross f is when the rolled material S is bitten, the upper and lower work rolls 11
This refers to a phenomenon in which the rotational speed of the knife temporarily decreases as shown in FIG. 2, and the impact drop amount is defined as TL/No.

Note that No. indicates upper and lower work rolls 1. The rotational speed of f before biting of the rolled material, ru, is the maximum value of the rotational speed drop of the upper and lower work rolls 1 and f in the impact drop generation area.

Conventionally, as a means to prevent the warping of the rolled material caused by the difference in the impact drop amount between the upper and lower work rolls, for example, a drive control system for the upper and lower work rolls has been introduced so that the impact drop amounts of the upper and lower work rolls are equal to each other. Either the rolling speed command value in the rolling process was controlled or the absolute amount of impact drop was reduced.

However, as described above, various factors are involved in the occurrence of warpage at the biting tip of the rolled material, and therefore the conventional means described above cannot reliably prevent warping of the rolled material.

In view of such conventional problems, the present invention is designed to reliably prevent the occurrence of warpage at the biting tip of the rolled material, and an example of its implementation will be described below based on FIG. 3. explain.

In FIG. 3, 1. f is the upper and lower work rolls in the reversible rolling mill, and 2 and 2' are the upper and lower backup rolls in the reversible rolling mill.

3.3' is a driving electric motor for the upper and lower work rolls 1, 1', and 4.4' is a rotational speed detector for each driving electric motor 3, 3'.

The electric motors 3, 3' are equipped with rotation speed detectors 4, 4', speed controllers 5.5', current controllers 6.6', voltage controllers 7.
7', gate pulse generator 8.8', thyristor 9,
9' (drive control system for the upper and lower work rolls 1, 1').

That is, for example, the electric motor 3 for driving the upper work roll 1
Regarding the rotational speed control, the rolling speed command value and the rotational speed detection value by the rotational speed detector 4 are given as input signals to the speed controller 5, and the comparison calculation value is sent from the speed controller 5. The signal is outputted and given as an input signal to the current controller 6.

Further, the detected value of the armature current (load current) of the motor 3 is given as an input signal to the current controller 6, which is compared with the output signal from the speed controller 5, and the comparison value is used as the current controller. 6 and is given as an input signal to the voltage controller 7.

The voltage controller 7 receives the armature voltage detection value of the motor 3 as an input signal, compares it with the output signal from the current controller 6, and uses the comparison value to generate a gate pulse from the voltage controller 7. given as an input signal to the device 8,
The phase of the firing angle of the thyristor 90 in the armature circuit of the motor 3 is controlled via the gate pulse generator 8, and the terminal voltage of the motor 3 is controlled.

Note that the rotational speed control of the driving electric motor 3' of the lower work roll f is performed in the same manner.

Therefore, the present invention provides the above-mentioned upper and lower work rolls 1. Rotational speed control device for drive electric motors 3 and 3' of f (
An impact drop correction amount signal is applied as a comparison calculation element to the current controllers 6, 6' in the drive control system of the upper and lower work rolls 1, 1' at the time of biting of the rolled material S. The amount of impact drop of the rolls 1, 1' is appropriately controlled to reliably prevent the occurrence of warpage at the biting tip of the rolled material S.

That is, as shown in FIG. 3, when rolling the material S to be rolled by the upper and lower work rolls 1 and 1', the rolling torque required to roll the material S to be rolled is predicted by the rolling torque calculator 0. At the same time, the upper and lower work rolls 1 are necessary to prevent warping at the biting tip of the rolled material S.
, 1' is predicted by an impact drop amount difference calculation unit 11.

The impact drop amount difference that does not cause warping and the upper and lower work rolls during normal rolling 1. Compare the predicted calculated value of the impact drop amount difference of f, and determine the impact drop correction amount so that both are equal, using the rolling torque, the work roll rotation speed before the rolled material is bitten,
The impact drop correction amount calculator 12 calculates the impact drop amounts of the upper and lower work rolls 1 and 1', and the calculated value of the impact drop correction amount is applied to each function generator 13, when the rolled material S is bitten. 13', it is supplied as a correction input signal to the current controllers 6, 6'.

Note that the means for inputting the impact drop correction amount signal to the current controllers 6, 6' through the function generators 3 and 13', respectively, when the rolled material S is bitten, is as follows. For example, the load cell 14 detects the biting stress of the upper backup roll 2 when S bites into the work rolls 1, 1', and the biting detector 15 is operated by the signal from the load cell J4 to detect this biting. The signal from the generator 15 is given as a trigger signal to each function generator 13 , 13 ′, so that each function generator 13
, 13' may be operated.

Here, the impact drop amount difference calculator 11, impact drop correction amount calculator 12, etc. will be explained.

The impact drop amount difference calculator 11 calculates the upper and lower work rolls 1.1' necessary to prevent warping of the curvature radius ρ as shown in FIG. 1 at the biting tip of the rolled material S.
This is to calculate the impact drop amount difference Xn.

The curvature % is given by the following equation (1) as a function of the difference Xn between the impact drop amount of the upper work roll and the impact drop amount of the lower work roll 1'.

”jp = jp (xn,・・・・・・・・・)・
(1) For example, fρ is one of the following experimental relational expressions.

/ρ=αo+”I Xn,,・・・・・・(1
') Note that "1 t ctO" is a coefficient mainly determined by roll characteristics such as a difference in roll diameter and a difference in hardness between upper and lower work rolls and the thickness of the material S to be rolled.

From the above equation (f), the impact drop amount difference Xn required to make the curvature y/p zero is expressed by the following equation (2) (calculated in the calculator 11).

XrL=-ao/a1...4 (2) Fig. 4 shows the plate thickness of the material S to be rolled 8 to 10a, the upper and lower work rolls], 1
This shows the experimental results of determining the impact drop amount difference Xn necessary to prevent warping at the biting tip of the rolled material S under conditions of a roll diameter difference of 1°89 mm and a hardness difference of 2.0. In this case, the impact drop amount difference X is -1°2φ.

Incidentally, the rolling torque calculator 1o calculates the rolling torque ゛1゛L from the rolling conditions before the pressurized abrasive S is bitten.
This is a predictive calculation.

Generally, the rolling torque TL is calculated from the torque arm coefficient λ, the contact projection length ld, and the rolling load P using the following formula (3) % formula % (3) In the rolling torque calculator JO, the torque arm coefficient λ, the contact projection length The predicted values of each variable of ld, rolling load P are given, and the calculation according to the above equation (3) is performed.

The impact drop correction amount calculation unit 12 calculates the impact drop amount difference The impact drop correction amount Z that makes the impact drop amount difference Xn equal is calculated before the rolled material S is bitten.

First, the impact drop amount difference Xn during normal rolling is calculated.

The impact drop amount L/No is the predicted rolling torque TL
, the rotational speed N of the work roll before biting of the rolled material. A functional expression such as is given by the following equation (4).

rL/No = f n/No(TL, No −
--) ---(4) And for example, fn/No1
I′i is the following formula: 0”/NOl = bo + b,
T L, + b2/N. ,......(4'
) Run 1 N. 1/-bu' + bt'TL1'
+ b”/ No, l””””’ (4, bo
, b, , b2 and l) O'+ b1/, b2' are coefficients, and equation (4) is the equation that calculates the impact drop amount rL +/N,1 of the upper work roll 1, (4")
The formula is the impact drop amount % of the lower work roll 1'. This is the formula to calculate I'.

The impact drop amount difference Xn between the upper and lower work rolls 1 and 1' during normal rolling is given by the following equation (5).

X n ” ” / Not ”' / NO! ' - Opening (5) Next, compare the impact drop amount difference Xn with the impact drop amount difference X7+ determined by the above formula (5), and check that they are equal. The impact drop correction amount 2 is determined so that

For example, when Xn>Xn, the impact drop correction amount to the upper work roll l is set to zero, and the impact drop correction amount to the lower work roll 1' is calculated.

In addition, if XrL<XtL, the impact drop correction amount for the lower work roll f is set to zero, and the impact drop correction amount for the upper work roll 1-. Rotational speed N of the work roll before biting the material. ,
Impact drop amount N. From the above, the experimental relational expression is given by the following equation (6).

z=fz(TL, No, 7/No,...
)・・・・・・・・・(G) Function f in the above equation (6)
For example, z is expressed by the following formula (6').

Z = co +CI TTJ1C2/No + cs
'/No ・・・・・・・・・ (6') Furthermore, co
+C1pC2+C3 is a coefficient, which is determined and applied to the upper and lower work rolls 1 and 1', respectively.

The function generators 13 and 13' are operated by a signal from the jam detector 15, and input the impact drop correction amount signal Z to the current controllers 6 and 6' as a waveform of a prespecified pattern. However, as the waveform, a single triangular waveform as shown in FIG. 5 was used, T was fixed, and ■ was adjusted.

Figure 6 shows the experimental results for the same load and the same biting speed. In this case, in order to make the impact drop amount difference Xn, for example, -2 inches, correction 1 to the lower work roll should be applied. Zero and shi, the amount of correction to the upper work roll is 0
038 and n are all you need.

As described above, when rolling a material to be rolled using a reversible rolling mill, the present invention provides the necessary rolling torque to roll the material to be rolled and the necessary rolling torque to prevent the occurrence of warping at the biting tip of the material to be rolled. The impact drop amount difference between the upper and lower work rolls and the impact drop amount difference between the upper and lower work rolls during normal rolling are predicted and calculated, and the impact drop amount difference that does not cause warping and the impact drop amount difference during normal rolling are calculated. An impact drop correction amount such that When the material is bitten, it is given as a correction input signal to the current controller in the work roll drive control system, so the impact drop amount of the upper and lower work rolls can be appropriately controlled, and therefore the biting tip of the rolled material 0 that can reliably prevent the occurrence of warping of parts.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram showing a state in which warping has occurred at the biting tip of the rolled material, Fig. 2 is an explanatory diagram of an impact drop,
Fig. 3 is a block diagram showing an example of the implementation of the present invention, Fig. 4 is a graph showing an example of the relationship between the impact drop amount difference and the curvature of warpage at the biting tip of the rolled material, and Fig. 5 is the impact An explanatory diagram showing an example of a drop correction amount signal,
FIG. 6 is a graph showing an example of the relationship between the correction amount and the impact drop amount. Applicant Kawasaki Steel Co., Ltd. Figure 4 Figure 5

Claims (1)

[Claims] When rolling a material to be rolled using a reversible rolling mill, the rolling torque required to roll the material and the impact drop of the upper and lower work rolls required to prevent warping at the biting tip of the material to be rolled. The amount difference and the impact drop amount difference between the upper and lower work rolls during normal rolling are predicted and calculated, and the impact drop amount difference that does not cause warping is made equal to the impact drop amount difference during normal rolling. The impact drop correction amount is determined by the rolling torque, the work roll rotation speed before the rolled material is bitten,
The impact drop correction amount is calculated from the impact drop amounts of the upper and lower work rolls, and the calculated impact drop correction amount is given as a correction input signal to the current controller in the work roll drive control system when the rolled material is bitten. Speed control method for reversible rolling mill.