JPS61199507A - Control method of forward slip in metallic sheet rolling - Google Patents

Abstract

PURPOSE:To perform stable high-speed rolling from the beginning by learning and correcting the friction factor of a model expression of friction factor by changing several conditions during rolling and regulating a forward slip, depending on an operated friction factor corresponding to new rolling conditions, to a proper value by controlling the several rolling conditions. CONSTITUTION:As a friction factor measured in rolling, changes in accordance with sheet thicknesses at the inlet and outlet sides, tensions at the front and back sides, a speed of rolling roll, a feeding rate of lubricating oil, a sheet temperature at the inlet side and a rolling load, during rolling; model expressions of friction factor are rearranged, learned, corrected and accumulated. When rolling is newly performed, a forward slip for rolling stock is obtained based on an operated friction factor corresponding to its rolling conditions, and the forward slip is regulated to a proper value by controlling the several rolling conditions, for instance a feeding rate of lubrication oil.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) This invention relates to an advanced rate control method in metal plate rolling.

(Conventional technology) High-speed rolling is attracting attention with the aim of improving productivity. When high-speed rolling is performed, the hydrodynamic lubrication area increases and the friction coefficient decreases. Accordingly, the neutral point approaches the roll bite exit, that is, the advance rate becomes smaller. Furthermore, when the lubrication conditions are good, the neutral point protrudes from the roll bite exit, that is, the advance rate becomes negative.

Conventionally, it has been said that if rolling continues with a negative advance rate, chattering and heat streaks will occur. However, when we actually measured the advance rate of the final stand in actual tandem rolling, the advance rate sometimes showed a negative value of θ ~ -3z, and troubles did not necessarily occur in the area where the advance rate was negative. I found out that it wasn't a translation. As a result of further experiments, it was confirmed that in order to enable stable rolling, it was necessary to keep the advance rate within an appropriate range (even a negative range).

In current actual operations, the wear of the rolls is controlled by the cumulative rolling weight, etc., and the rolls are replaced at an early stage to prevent the above-mentioned rolling abnormalities. However, rolling abnormalities still occur two to three times a day, and rolling control that enables high-speed stable rolling has been desired.

JP-A-55-10 as a rolling method for high-speed stable rolling
There is a rolling technique disclosed in No. E187. This technology dynamically controls the roll speed, rolling reduction, rear tension, and front tension in order to keep the advance ratio constant or within a certain range.

(Problems to be solved by the invention) However, according to the conventional rolling technology described above, changing the roll speed directly affects production, changing the tension increases the burden on seaming and automatic plate thickness control, and Changing the rolling reduction ratio, for example, will result in off-gauge in the final pass, so any change is impractical.

Furthermore, since the control amount cannot be calculated in advance, rolling abnormalities cannot necessarily be prevented.

During rolling, the advance rate can be easily determined by actually measuring the circumferential speed of the rolling rolls and the exit plate speed. However, as mentioned above, by keeping the advanced rate within an appropriate range,
In order to perform rolling, it is necessary to know the advance rate before starting rolling. Of course, if the rolling conditions change, the advance rate will change. Conventionally, there has been no method to control the advance rate in response to changes in rolling conditions. For these reasons, a method for accurately and easily controlling the advance rate has been desired.

(Configuration of the Invention) The configuration of the present invention will be explained according to the flowchart shown in FIG.

The advanced rate control method for metal plate rolling of this invention first detects the entrance and exit plate thicknesses, front and rear tensions, rolling roll speed, exit plate speed, lubricant supply amount, entrance plate temperature, and rolling load during rolling. do.

It is not necessary to directly detect the inlet plate thickness, outlet plate thickness, and outlet plate speed by a detector in the rolling mill that predicts the advance rate.The plate thickness and plate speed are detected in a rolling mill upstream or downstream of this rolling mill. death.

The above-mentioned inlet side plate thickness, etc. may be calculated according to the constant mass flow law.

That is, during regular rolling, the mass flow is constant between stands, so the plate thickness and plate speed are simultaneously detected somewhere in the upstream stand, and the mass flow is determined by calculating the product of the plate thickness and plate speed. Using this mass flow, if the plate thickness or plate speed is detected at the entrance and exit sides of the stand where the advance rate is predicted, the plate speed or plate thickness can be determined by calculation. The above method is also applicable to downstream stands.

In addition, to determine the plate thickness and plate speed even during irregular rolling, either detect the plate thickness and plate speed at the input/output side, or simultaneously detect the plate thickness and plate speed at either the input/output side. The mass flow can be obtained by determining the mass flow, and the plate thickness or plate speed can be detected on the other hand, and calculations can be performed using the mass flow to calculate the plate speed or plate thickness. In this case, it is necessary to adjust the detection timing of the detector. Needless to say.

The actually measured friction coefficient μg is calculated based on the detected value and the rolling conditions set in advance. The formula for determining the measured friction coefficient μm is expressed as a general formula in the form of the following formula (1).

uap=iLavcfs, OG, llV, H, h, ni, R)...(1) Here, J$ is the actual advanced rate obtained from the above detected value,
(Jb, Crt is the plate tension, H is the inlet side plate thickness, h is the outlet side plate thickness, k is the deformation resistance of the material, and R is the roll radius.

Next, based on the measured friction coefficient μda, the influence coefficients of the variables of the friction coefficient model formula on the friction coefficient are corrected. The friction coefficient model formula uses the inlet and outlet plate thicknesses, rolling roll speed, and lubricant supply amount as variables. The friction coefficient model formula is as follows.

μm=μ0+Δμ...(2) here.

μ0: Friction coefficient Δμ under standard rolling conditions (set rolling conditions) = Influence of increment of each rolling factor from standard rolling conditions on friction coefficient: Rolling factor, that is, a variable in the friction coefficient model formula, with a subscript indicates the type of variable.

It is expressed by a number and an approximate formula based on experiments.

The influence coefficient of each variable on the friction coefficient in the friction coefficient model formula (2) is corrected based on the measured friction coefficient determined by the above formula (1), and the above operation is repeated to learn and modify the influence coefficient. In learning correction, a large amount of collected data is used to correct influence coefficients, that is, regression parameters, for example, by multiple regression analysis. Regardless of the multiple regression analysis method, the influence coefficient may be determined as follows, i.e., using the formula (+
) The rolling conditions are changed by the number n of variables, and the values of the variables are actually measured and the friction coefficient uap is determined. The n equations obtained from this are combined to calculate the influence coefficient.

The friction coefficient μs- corresponding to the new rolling conditions is determined by a friction coefficient model formula obtained by learning and modifying the influence coefficient. Then, the advance rate fs is determined based on this calculated friction coefficient tL. The formula for determining the advance rate f is the following general formula (
It is expressed in the form of 0.

fs = fs Cu, En, (17, H, h, ni, R
)...(4) Next, it is determined whether the obtained advanced rate fs is within an allowable range.

If the advance rate fs is not within the allowable range, an appropriate rolling factor is operated to bring the advance rate js to an appropriate value. The manipulated variable of the rolling factor can be obtained from the advanced rate model formula.

The advanced rate model equation is expressed by the following equation (5).

Js = fs. +Δf$... (5
)here.

J$. This is the advance ratio ΔJ in the two-standard rolling state, and the influence of the increment of each rolling factor from the two-standard rolling state on the advance ratio.

Therefore, the manipulated variable Δin is as follows.

Here, Δfs is the advanced rate fs obtained using equation (4).
and the allowable limit value. The appropriately selected rolling factor, for example, the entrance plate thickness, is calculated according to the above formula (7).Xl! I will arrange it.

(Operation) The influence coefficient of the friction coefficient model formula is learned and corrected using the measured friction coefficient μ4. Therefore, the calculated friction coefficient μm can be determined with high accuracy, and the calculated friction coefficient ILS1. l
The advanced rate f can be predicted with practical accuracy by using f as one of the variables.

The predicted advance rate fs can be kept within an allowable range by determining and adjusting the manipulated variable of the rolling factor using the advance rate model formula.

(Example) 9th IM I+;

In rolling 4i11, the work roll 2.3 driven by the motor 4 rolls the strip S. Deflector rolls 5.6 are arranged on the inlet and outlet sides of the rolling mill I, respectively. Furthermore, a lubricating oil supply nozzle 7 and a coolant supply nozzle 8 are arranged on the entry side of the rolling @1.

In the rolling mill configured as described above, an example of controlling the advance rate will be explained according to the flowchart shown in FIG.

First, during rolling, the tapped plate thickness h, the front and rear tensions Tb
, T, rolling roll speed vR, inlet plate speed vX, outlet plate speed v0, lubricating oil concentration CL and supply amount Q, inlet plate temperature TP, rolling load P and roll pending force F
Detect.

That is, in the rolling mill 1, the rolling load P is detected by the load cell 11, and the circumferential speed vR of the workpiece and the rolls 2 and 3 is detected from the rotational speed of the motor 4. Note that the roll pending vehicle F is detected by a device (not shown).

On the entry side of the rolling mill 1, the material speed v■ is detected from the rotational speed of the deflector roll 5, and the plate tension Tb is detected from the force acting on the deflector roll 5. Further, the radiation thermometer 12 detects the plate temperature TP, as well as the amount CL and supply amount Q of the lubricating oil jetted from the nozzle 7.

On the exit side of the rolling mill 1, the material speed V0. The plate tension T is detected from the force acting on the deflector roll 6. Further, the thickness of the plate is detected by the radiation thickness meter 13.

All measured values detected as above are stored in computer 1.
4 is input.

Based on the above detected values, the computer 4 calculates the following values.

Rolling ratio f = 1 - Actual rolling load Pey = P - F b Rear tension = □ b rf Front tension port = - b ... (8) Here, b is the plate width, and C is the advanced rate slide coefficient (It is a constant used when the advance rate is in the negative region, and is unique to the stand and differs depending on the steel type and roll conditions.)

The measured friction coefficient μm is determined based on the above calculated value and the rolling conditions set in advance. The method for finding it is as follows.

If the roll angle at the neutral point is φ, the following equation (9) can be obtained from the geometrical relationship.

Also, Bland & Ford
), the roll angle φ1 at the neutral point is determined by the formula (10
).

However, ... (11) Here, if equation 1 (11) is solved for the friction coefficient μ, equation (13) corresponding to the above equation (1) is obtained.

Moreover, if HrL is expressed by the measured advanced rate Jey using equations (9) and (10), it becomes as follows.Therefore, by substituting equation (14) into equation (13), the actual measured advanced rate Jey can be expressed as follows. Friction coefficient μ
αP can be found.

By the way, in order to find the actually measured friction coefficient Key, use the formula (13
), the deformation resistance of the roll bite inlet and outlet requires , ko. The value of 0 for the deformation resistance is determined as follows.

first.

k=fL(r+m)' ”(1
Assume a sentence in 5).

Here, the average rolling reduction rate r=0.4 rb +o, s rf
Also, the constants m and n are determined in advance by a tensile test of the material. H& is the thickness of the material.

When k is determined by equation (12), the deformation resistance +kO can be found as kA=i(rb+m)nko=l(r4+m)rL=(1B).

On the other hand, the theoretical rolling load P is determined by the following equation (17) based on Hill's theory.

Pka=bk'kF17 Hire 1 Go DP...(17
) Here, R is the radius of the flat roll, and DP is given as the friction number. k is a tension correction term and is a constant.

Further, the flat roll radius R is given by, for example, Hitchcock's (formerly Tchcock) theory.

and.

If the theoretical value P, -=actual value PetP, then the assumption in equation (15) is favorable, and
Determine the deformation resistance and the measured friction coefficient LLeKP.

The deformation resistance thus determined and the measured friction coefficient μg are stored in the computer 14 together with the rolling conditions.

Next, the friction coefficient model formula will be explained.

The effects of various rolling factors on the friction coefficient were analyzed and tested. As a result, it was found that the relationship between the friction coefficient μ and each rolling factor can be formulated as follows.

μ=Ar −r+Cr μ=Aol; ・ Mixture + CG μ=Aov・07+Co7 μ= AVR-exp (BVR-vR)+Cv2μ
= Ao −exp (Bq −Q)+C.

μ=AcL−exp(BcL−CL)+CcL
μ=AT, ・TP+C.

μ=AR-R3・ μ=A*, ・Ra+CI+.

...(18) However, ReL represents the roll roughness, A, B, C are constants, and I represents the type of each rolling factor.

Also, according to experiments, the difference between the roll roughness Ra and the cumulative rolling weight W.

R@=AI+,・exp (Byoi.・W)+Cwa
It turns out that there is the relationship (18). Using this relationship, the last equation of equation (15) can be written as μ=AV-exp (Bv-W)+Cv...(20
) or using the number N of rolling coils instead of the integrated rolling weight W, μ= AH-e! 'p (BN ・N) + CM
−(21) can be rewritten.

Therefore, the friction coefficient model equation (2) can be expressed as the following equation.

μm=μG+Ar”Δr+A(5・Δ%+Aay−Δm
+AvR-Bv12-ezp (BvlI-VB)
・ΔVR+AQ −BQ −exp (BQ−Q)−
ΔQ +AcL-BeL-exp (BcL-CL
)・ΔCL+ A Tp-ΔTp +A, -Bv-ex
p (Bv −W) ・ΔW+AR−Bl1t−1 “R・ΔR...(22) Actual measurement μα obtained by equation (13) based on the detected value
By substituting the P friction coefficient into the calculated friction coefficient μ in equation (19), the regression parameters of the friction coefficient model equation (22) are learned and corrected by multiple regression analysis. Learning and modification of the regression parameters continues during rolling.

From this, the calculated friction coefficient US- can be calculated with high accuracy based on the friction coefficient model formula (22).

In this example, since the lubricating oil concentration CL is a constant concentration, there is no need to consider it, and r=r, 06=(1,0J=07.V*=VR, T
Assuming that P = TP and Q = Q, that is, Δin = 0, and W = W, , t, the following calculated friction coefficient μwan
I'm looking for t. W, is the following rolling load.

Therefore, equation (18) is expressed as jj
*, t = μ. +Av-e! p(Bv-WM,t)・W
2 also becomes...(23).

Next, based on the above calculated friction coefficient LL, advance rate fss
Calculate -. That is, the advanced rate model equation (13)
By substituting the calculated friction coefficient μ 佽 obtained by the friction coefficient model formula (22) into , the advance rate f ”wit corresponding to the newly set rolling conditions is determined.

Furthermore, by adding the advanced rate slide coefficient C to the above equation (8), the value of the advanced rate can be expanded to a negative region,
Even if the first a rate becomes negative, this can be predicted.

The computer 14 determines whether the advance rate f'tart, obtained as described above, is within the allowable box concave circle.

If the advance rate f''sawt is not within the allowable range, the advance rate J is adjusted in a linear manner.

The magnitude of the influence of the rolling factor on the advance rate f, that is, the influence coefficient, is determined by the following equations (24) to (28). The above equation (6) is expressed as the following equation (20).

here.

(25) However, in the case of input=h, by using the above equation (24), it is possible to easily obtain the accurate advance rate characteristic and the influence coefficient of each rolling factor on the advance rate. For example, if the entrance plate thickness H or lubricant supply amount Q is selected as the rolling factor, a "or a c 6.8" The manipulated variables of the entrance plate thickness H or lubricant supply amount Q are these limits. If the value exceeds the value, replace the work roll itself. In addition, to adjust the entrance plate thickness H, the pass schedule of the preceding rolling mill is changed.

Here, an example of controlling the advanced rate J is shown.

In tandem rolling, a coil with a plate thickness of 2.51 mm is rolled into a plate with a plate thickness of 0.
．． It was rolled to 50+wm, during which time the advance rate f was adjusted to an appropriate value. The number of rolled coils was 50 pieces.

FIG. 4 shows an example in which the advance rate f is kept within an appropriate range by manipulating the entry side plate thickness H. When 33 first coils were rolled, the advance rate fs decreased to approximately oz. Therefore, from the 34th grain onward, the pass schedule of the rolling mills up to the previous stage was changed and the entry side plate thickness H was adjusted so that the leading a ratio f did not fall below Oz.

Further, FIG. 5 shows an example in which the lubricating oil supply amount Q is manipulated to keep the advance rate f within an appropriate range. When 30 first coils were rolled, the advance rate J$ decreased to approximately oz. Therefore, adjust the lubricating oil supply amount Q from the 34th wood coil,
The advanced rate fs was prevented from becoming less than oz.

(Effects of the Invention) As explained above, according to the present invention, even if the rolling conditions change, the advance rate can be predicted with sufficient accuracy for practical use. Then, by adjusting rolling factors such as lubricant supply amount using the predicted advance rate, the advance rate is maintained at an appropriate value, preventing chattering, heat streaks, etc., and performing stable high-speed rolling. Can be done.

[BRIEF DESCRIPTION OF THE DRAWINGS] Fig. 1 is a flowchart explaining the present invention in detail, Fig. 2 is a configuration diagram of an apparatus for carrying out the invention, Fig. 3 is a flowchart explaining an embodiment, and Fig. 4 is a flowchart explaining the present invention. FIG. 5 is a graph showing an example of control in which the advance rate is kept within the proper range by manipulating the side plate thickness, and FIG. 5 is a graph showing an example of control in which the advance rate is kept within the proper range by manipulating the lubricating oil supply amount. l...Rolling mill, 2.3... Work roll, 4...
Motor, 5, 6... Deflector roll, 7... Lubricating oil supply nozzle, 8... Coolant supply nozzle, 11
...Detector, 12...Temperature detector, 13...Plate thickness gauge, 14...Computer, S...Strip.

Claims (1)

[Claims] During rolling, the inlet and outlet plate thicknesses, front and rear tensions, rolling roll speed, outlet plate speed, lubricant supply amount, inlet plate temperature, and rolling load are detected, and based on the detected values and preset rolling conditions. The coefficient of influence of each variable on the friction coefficient is determined based on the measured friction coefficient in the friction coefficient model formula, which uses the input and exit plate thicknesses, rolling roll speed, and lubricant supply amount as variables. correct,
The above operation is repeated during rolling to learn and modify the influence coefficient, calculate a calculated friction coefficient corresponding to new rolling conditions based on the learned and corrected friction coefficient model formula, and use the calculated friction coefficient to calculate a new A method for controlling an advance rate in rolling a metal plate, characterized by determining an advance rate corresponding to rolling conditions, and controlling a rolling factor so that the determined advance rate is within an allowable range.