JPS6272411A - Speed control method for continuous rolling mill - Google Patents

Abstract

PURPOSE:To quickly absorb tension variations between stands by correcting a roll circumferential speed at an adjacent stand based on both a difference between a predictive value and an actual value of a rolling schedule setting calculation and a plate thickness variation amount during a plate thickness control. CONSTITUTION:A quotient by dividing a difference between the prescribed outlet side plate thickness of a rolling shedule setting calculation and an actual outlet side plate thickness just after biting by the prescribed outlet side plate thickness at both adjacent stands is obtained and a roll circumferential speed of either stand is corrected to the extent of a proportional amount to the difference between the quotient at both the stands. An amount of drafting down movement and an actual outlet side plate thickness are monitored and a difference between an actual outlet side plate thickness variation amount and an arithmetic value of a proportional variation amount in a plate thickness depending on the drafting down movement is obtained. Then, a roll circumferential speed of either adjacent stand is corrected. to the extent of a proportional amount to a quotient given by dividing the above obtained difference value by the actual outlet side plate thickness. In this method, a tension variation between adjacent stands is absorbed quickly.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a speed control method for compensating for changes in tension between two adjacent stands of a continuous rolling mill.

(Prior Art) Conventionally, as a method for controlling the tension between stands, a method is performed by providing a looper device between the stands and controlling the height and pushing force of the looper (referred to as looper control).
Alternatively, a method (referred to as loopless control) of controlling the speed based on the tension estimated from the load and torque of the rolling mill is common. (Tension control section in "Theory and Practice of Plate Rolling" edited by the Japan Iron and Steel Institute, published on September 1, 1989, published by the Japan Iron and Steel Institute) (Problems that the invention aims to solve) However, especially when the tension fluctuates rapidly, When looking at the controllability immediately after the tip of the rolled material is bitten, which requires a quick response, in the former louver control, the time from when the looper stands up to when it contacts the rolled material is dead time. However, with the latter looperless control, an effective control effect cannot be expected because the tension detection accuracy in the multi-stage stand is lower than that in the previous stage stand, and the control product is significantly reduced. .

In view of the above-mentioned background, the present invention was developed to solve the problem of excessive tension fluctuations occurring between adjacent stands, particularly at the leading end of a rolled material, due to errors between predictions and actual results in rolling schedule setting calculations, Fj, rg, the continuous rolling mill is designed to quickly absorb sudden changes in tension that occur due to the sharp rolling movement at the tip of the material due to the absolute value AGC function and high-speed X-ray monitor function in the control. The object is to provide a speed control method.

(Means for Solving the Problems) The present invention provides a speed control method for compensating for changes in tension between adjacent stands of a continuous rolling mill. and,
The value obtained by dividing the difference between the actual outlet plate thickness and the actual outlet plate thickness immediately after the material is caught in the rolling stand by the designated outlet plate Jv (or the actual outlet plate thickness) is calculated for each of the two adjacent stands on the upstream side, and Immediately after the material is bitten into the
The roll circumferential speed of the upstream stand or the relevant stand is corrected by an amount proportional to the difference between the two, and rolling is continued for a certain period of time immediately after the material is bitten by the relevant stand while monitoring the rolling opening and the actual thickness of the plate on the exit side. By multiplying the moving mouth by a parameter determined from the mill constant of the rolling mill and the plasticity coefficient of the material, the amount of change equivalent to the plate thickness due to the rolling movement is determined, and the difference between this value and the actual amount of change in plate thickness on the exit side is determined. The present invention is characterized in that the roll circumferential speed of the upstream stand or the stand concerned is corrected by a value proportional to the value obtained by dividing the value of this difference by the actual sheet thickness on the exit side.

Excessive tension fluctuations that occur when rolled materials are bitten are mainly caused by predictions made in the rolling schedule setting calculations.Due to errors between the rolling load and the actual rolling load, the actual plate thickness cannot be obtained as per the setting calculations, and therefore the adjacent This is caused by the mass flow between the stands. The amount of unbalance can be almost ignored since the change in the advance rate is small, and can be expressed as shown in the following equation.

・・・・・・・・・Formula (1) However, Immediately after the actual plate thickness value is obtained by the material being bit into the relevant stand, the mass flow imbalance rate is calculated using the above equation (1), and then By correcting, for example, the roll circumferential speed of the upstream stand by a proportional amount, it is possible to suppress excessive tension fluctuations that occur during biting. This is called first control. In addition, roll circumferential speed correction 1Δ■
1-1 is given by the following equation (2).

The actual exit plate thickness can be determined, for example, from the actual rolling load and roll gap using a generally known gauge meter plate thickness calculation formula.

Next, the actual exit side plate thickness and rolling movement amount are monitored for a certain period of time immediately after the material is bit into the material, and errors that cannot be absorbed by the first control alone or sudden movements in rolling due to plate thickness control at the leading edge of the material are monitored. We will explain a control method to quickly absorb the tension fluctuations caused by this, which utilizes the knowledge that the plate thickness changes with the behavior of the tension.

That is, by using the actual plate thickness immediately after the stand biting as a reference and monitoring the change in the actual plate thickness from there, it is possible to estimate the change in tension that occurred at the time of biting. However, in this case, in addition to tension changes, the factors that cause plate thickness changes include changes in rolling reduction due to plate thickness control, and changes in rolling load due to temperature fluctuations, so we devised the following method to distinguish between these. did.

First, the amount of change equivalent to the plate thickness caused by changing the rolling reduction is determined using the following equation (3).

However, when the on value is determined, the actual thickness change is calculated using the following formula (4),
By taking the difference from the plate thickness equivalent change amount corresponding to the previous reduction change, the plate thickness change amount mainly due to tension fluctuation is given by equation (5).

Δhi (actual) = hi −hi (Lo
ck on) ・++-(Formula 41 However, actual handling thickness lock-on value * Δhi=Δhi (actual)−Δhi (Loc
k on )・・・・・・Equation (5) However, Δhj*: Amount of plate thickness change due to Fi stand tension fluctuation Looking at the plate thickness change due to temperature fluctuation, which is not considered here, the tip part when the rolled material is bitten Since the control period can be shortened compared to the pitch of temperature fluctuations caused by skid marks, thermal rundown, etc., it can be almost ignored. In this case, the technical point of accurately detecting the amount of plate thickness change due to tension fluctuations is The aim is to set the lock-on timing immediately after biting, which is a reference for starting control, as early as possible compared to the time constant of tension generation caused by speed imbalance immediately after biting.

Therefore, by using the amount of change in plate thickness due to tension fluctuation determined by equation (5), for example, the roll circumferential speed of the upstream stand is corrected for a certain period of time immediately after the material is bitten, by the amount determined by equation (6) below. By doing so, it is possible to quickly absorb sudden tension fluctuations occurring at the tip of the material. This is called second control.

However, [ΔVi-1: Low at upstream Fl-1 stand] By using the second control together with the first control described above, the effect becomes very large.

FIG. 1 shows an embodiment of the invention.

In the figure, 7.8 is the speed control device of rolling mill 1.2,
The rolled material 3 is flowing in the direction from the rolling mill 1 to the rolling mill 2,
Let us now temporarily consider the rolling mill 2 side as a speed reference stand. Reference numeral 4 denotes a control computer, which has a model for calculating the amount of roll circumferential speed correction related to the first control and second control described above, and has a model that calculates the roll circumferential speed correction amount related to the first control and second control, and calculates the load detectors 9 and 10 installed in the rolling mill 1.2 and the roll gap. Rolling load signal p input from detector 17.18 and speed detector 11.12 attached to mill motor 5.6,
, p, and the roll gap signals S+-1, Si and roll peripheral speed signals Vi-1, Vi, calculate the amount of speed imbalance between adjacent stands for a certain period of time immediately after the material is bitten, and calculate it. Roll circumferential speed correction amount ΔV for
1-! is outputted to the speed control device 7 of the rolling mill 1, at which time it is added to the speed reference EF Vl-1 from the setup or looper control through the adder 14.

Note that the ('iiJ positive signals from the load detectors 9 and 10 are simultaneously input to the biting detection circuit 13, and the material biting signal detected here is input to the control computer 4 to determine the control start timing. It is offered to.

In the above, the downstream rolling mill 2 side is used as the speed reference stand,
The explanation was given using the example of controlling the roll circumferential speed of the upstream stand (i-1), but it is also possible to reverse the polarity of the output and
Moreover, by setting the speed ratio of both stands higher, it is also possible to control the roll circumferential speed of the downstream i-stand.

〔Example〕

The present invention is applied to the speed control of a hot finishing continuous rolling mill consisting of 6 stands (Fl to F6), and the target amount is 2.
Figures 2 and 3 show the results of one roll of a material having a width of 1040 am.

Figure 2 shows the state of the speed control output based on the present invention for each stand except the F6 stand, which is the speed reference stand. As shown in Figure 3, approximately 0
．． Starts control at an early timing of 5 seconds (conventional looper control takes several seconds) and outputs to quickly absorb mass flow imbalance (in this example, in the direction of speed increase)
It can be seen that he is giving out. Note that this output is cleared as soon as the material leaves the stand. In addition, the horizontal axis of FIG. 2 is time (SEC), and the digits are %, which is expressed as the rating of the motor (-knob speed (1-a)/ratio).

FIG. 3 shows a chart of the final plate thickness and width after rolling in a finishing mill, comparing the cases according to the present invention and the case according to the conventional method (looper control). It can be seen that by introducing this, changes in plate thickness and plate width at the tip due to excessive tension fluctuations during material biting, which occurred when conventional rolling schedule setting calculation errors were large, were almost completely absorbed.

〔Effect of the invention〕

As described above, the present invention is an invention that improves root passability immediately after material is bitten in a continuous rolling mill, and also contributes to improvements in quality such as plate thickness and plate width.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing one implementation of the present invention for a deaf person;
The figure is a chart showing the state of the speed control output based on the present invention. Figure 3 is an enlarged view of section A in Figure 2. FIG. 4 is a plate thickness/width chart comparing the Nyorori J-ka of the present invention with that of the conventional method. 1.2...Rolling mill, 3...Rolled material, 4...Control computer, 5.6...Electric motor, 7.8...Speed control device, 9.10...Load detection Vessel, 11.
12... Speed detector, 13... Biting detection circuit,
14...Adder, 15.16...Subtractor,
17.18...Roll gap detector.

Claims (1)

[Claims] In a speed control method to compensate for tension changes between adjacent stands of a continuous rolling mill, the designated exit plate thickness determined by rolling schedule setting calculations and the actual exit plate thickness immediately after the material is bitten by the rolling stand. The value obtained by dividing the difference between the two by the specified outlet plate thickness (or the actual outlet plate thickness) is calculated for each of the two adjacent stands on the upstream side, and immediately after the material is bitten into the stand, In addition to correcting the roll circumferential speed of the upstream stand or the relevant stand by the amount determined, the rolling machine adjusts the amount of reduction movement while monitoring the amount of reduction movement and actual plate thickness on the exit side for a certain period of time immediately after the material is bit into the stand. Multiply the mill constant by the parameter determined from the plasticity coefficient of the material to find the equivalent change in plate thickness due to the rolling movement, find the difference between this value and the actual thickness change on the exit side, and calculate the value of this difference. A speed control method for a continuous rolling mill, characterized in that the circumferential speed of a roll on an upstream stand or the stand concerned is corrected by an amount proportional to a value divided by the actual exit plate thickness.