JPS5944130B2 - Automatic plate thickness control method - Google Patents

Description

[Detailed description of the invention] The present invention relates to an automatic plate thickness control method for a rolling mill.

Conventional automatic plate thickness control methods can be broadly classified into the following two types.

That is, (I) Now, assuming that the roll opening is 81, the rolling pressure is P1, and the mill rigidity is M, the plate thickness at the exit side of the rolling mill is expressed by the following formula (2).

h=S+P/M・・・・・・・・・■ At the start of automatic plate thickness control, based on the formula ■, standard plate thickness ho,
After that, calculate the exit side plate thickness hχ at each time point, and calculate the difference between this and the reference plate thickness ho−hχ;・・・・・・■ (constant α) and drive the screw down motor until △h = o (roll down motor speed control); ■ The amount of screw down movement △S to absorb △h; △S-△h-△P/M・・・・・・■ (△5=So-8z, △P=Po-PZ, S.

and Po are the roll opening degree and rolling pressure, respectively, when the standard plate thickness is ho, and Sχ and Pχ are the roll opening degree and rolling reaction force, respectively, when the exit side plate thickness is hχ.

), and control the amount of roll-down movement ΔS according to formula (2) (down-position control method).

In method (I) above, the speed of the reduction motor is controlled in proportion to the amount of deviation from the reference value at each point in time (hereinafter referred to as gauge error amount), and since the gain α is constant, the skid The control system will not follow up properly at areas where plastic resistance suddenly changes, such as black bands caused by marks or descaling spray, and in the worst case, the response of the control system will be black at areas where plastic resistance suddenly changes, such as black bands. It appears in the normal plastic resistance area located next to the band, and may cause corrugations (unevenness) in the board thickness.

In the method (■) above, the gauge error amount corresponding to the rolling reduction correction amount is calculated, the deformation resistance is calculated from it, and the deformation resistance is learned. By doing so, the roll opening correction amount is corrected and the roll opening correction amount is always adjusted. Although the rolling condition can be fed back to the automatic control system, since the correction is made through position control of the reduction screw, optimal control that smoothly absorbs gauge errors cannot be achieved.

In other words, the moving speed of the reduction screw is always controlled by the gain of the position control, and for example, if you instruct the reduction screw to move down by 1 degree or 2 mm,
In the latter case, the movement speed will not be twice that of the former case,
In particular, the control system does not smoothly follow areas where the plastic deformation resistance changes suddenly, such as black bands.

Therefore, an object of the present invention is to provide an automatic sheet thickness control method that allows control to smoothly follow portions where plastic deformation resistance suddenly changes, such as a black band.

In order to achieve the above object, in the present invention, the reduction control against gauge errors is performed by controlling the speed of the reduction motor, but in this case, the speed gain is made variable and the control gain of the reduction motor speed is adjusted to include plastic deformation resistance and mill rigidity. To reflect.

If the plastic deformation resistance is K, then the roll reduction correction amount △S,
The relationship with the gauge correction amount △h is as shown in Fig. 4, when the roll opening degree is related to △S, according to the characteristic curves CLI to CL3 showing the plastic deformation resistance and the mill rigidity M, αd=bd -M=(△S-△h)・M1 αd-cd- has a relationship of -△h-K, (
△S - △h) ・M - △h -, °, △S - M = (M0K) ・△h Therefore, the correlation between the plastic deformation resistance and the mill stiffness M can be found.

Therefore, VM=α・(1+/M;・・△h・・
The gain of the speed VM of the rolling motor, the plastic deformation resistance, and the mill rigidity M can be introduced into the relationship .

If the rolling motor speed gain is determined in this way, the rolling speed will increase as the plastic deformation resistance increases, and when rolling a plate whose plastic deformation resistance varies depending on the part,
Since plate thickness control follows plastic deformation resistance, it smoothly follows black bands and the like.

In the following, the present invention will be explained in detail by exemplifying the configuration of an apparatus used to carry out the present invention.

The roll opening degree S and the rolling reaction force P are the same as before.
As shown in the figure, they are detected by a rolling position detector such as a potentiometer and a rolling reaction force detector such as a load cell, and a roll opening degree signal S and a rolling reaction force signal (i) appear at their signal output ends. These output signals are
The voltage is supplied to the screw down motor speed control circuit shown in FIG.

The roll opening signal S is supplied to holding circuits 1 and 2 via gates G1 and G2.

A gate pulse A having a constant period of 2T shown in FIG. 2 is supplied to the gate G1, and the gate is opened only during the pulse width τ.

A gate pulse B having a constant period of 2T shown in FIG. 2 is supplied to the gate G2, and the gate is opened only during the pulse width τ.

Pulses A and B are offset by a time T, as shown in FIG.

Pulses A and B are sampling pulses.

The holding signal of holding circuit 1 is supplied to adder 5 and inverter 4 via gates G3 and G5, and
The hold signal is supplied to adder 5 and inverter 4 via gates G4 and G6.

The output of inverter 4 is supplied to adder 5.

Gate G3. G6 and gate G4. Gate pulses A and B are supplied to G5, respectively.

Therefore, at the output end of the adder 5, the difference Si- between the roll opening degree Si at a certain point and the roll opening degree 5i-1 before that
'-8i-ΔS is output.

This point will be explained in detail. At time t1 when pulse AI (Fig. 2) exists, the output of holding circuit 1 is the sampling value SA1 at that time, but the output of holding circuit 2 is
This is the sampling value SB1 for the previous sampling pulse B1.

Therefore, at time t1, gates G3 and G6 are opened and adder 5 receives SA1 and -8B1.

Therefore, the output ΔS of the adder 5 is the difference in roll opening degree at each point in time between to and tl.

At time t2 when pulse B2 exists, the output of holding circuit 1 is the previous sampling value SA1, but the output of holding circuit 2 is
The output is the sampling value SB2 at that time.

Therefore, at time t2, gates G4 and G6 are opened and adder 5 receives SB□ and -SA1.

Therefore, the output S of the adder 5 becomes the difference in the roll opening degree at each point in time between tl and 12.

Similarly, at time t3, the output ΔS of the adder 5 is t
Roll opening difference between 2 and t3 SB2 8B3
Therefore, at time t4, it becomes 5B3-8A3.

Therefore, in this example, the sampling period is T, and the deviation ΔS from the previous roll opening degree is calculated for each period and supplied to the divider 11.

On the other hand, the roll reaction force P is Input terminal INF in the form of - is supplied to the adder 3.

The roll opening degree S is also supplied to the adder 3, and the following signal appears at its output.

This signal is supplied to the holding circuits 6 and 7 and to the inverter 15 via gates G7 and G8.

is game It is equal to the plate thickness H.

The outputs of the holding circuits 6 and 7 are the gates G9, GlO, G
11, adder 10 and inverter 9 via G12
supplied to

Gates G7 to G12 are controlled by sampling pulses A and B in the same way as gates G1 to G6, and the output of adder 10 contains the difference ΔH between the gauge plate thickness at a certain sampling point and the sampling plate thickness before that. This is supplied to the divider 11, where the division "S!H" is performed.

The output ΔS/6H of the divider 11 is applied to the gate G13 or G1.
4 to the holding circuit 13.

Therefore, from the holding circuit 13, I get the output, which is It is supplied to the adder 14 via the variable resistor 22.

The output of adder 14 is supplied to holding circuit 12 through gate G15 or G16, and also to multiplier 19.

The output of the holding circuit 12 is sent to the adder 1 via a variable resistor 23.
4.

The adder 14 and the variable resistors 22 and 23 are used to make the control smooth, and the values based on the previous sampling value and the current sampling value are taken in at a ratio of (1-β):β. It has the function of adding together.

In this case β is 0−J<1.

According to this, disturbances due to abnormal signals are avoided.

The variable resistors 22 and 23 have adjustment arms that are interlocked so that when one is at β, the other is at 1-β, forming a two-interlocking volume structure 20.

The adder 14 has an initial setting value set at switch S at the start of operation.
2.

Since the inputs that occur at the start of operation, that is, when there is no plate material between the rolls, are unreliable, a reasonable calculated value determined in equipment design is input as the initial setting value.

As described above, at each control point Namely is calculated and input to the multiplier 19. be done.

At the start of operation, a predetermined plate thickness ho is input to the holding circuit 21 via the switch S3.

During operation, switch S1 is activated when the plate thickness can be considered optimal.
is closed and its value is held in the holding circuit 21 as a reference value.

The output of the holding circuit 21 is supplied to the adder 17.

The plate thickness signal, which changes every moment, is supplied to an adder 17 through an inverter 15.

Therefore, at the output end of the adder 17, the plate thickness error △h=h
O-h appears, which is passed through amplifier 18 to multiplier 1
9.

The multiplier 19 is A constant value is given to the product of the signal of and the signal of △h. Output of value multiplied by α will occur.

This output signal is 2. Used for speed control of screw reduction motor.

As described above, in the automatic plate thickness control method of the present invention, the heating condition is controlled by the speed of the rolling motor, and the relationship is proportional to not only the plate thickness error △h but also the plastic deformation resistance K. The control responds smoothly and quickly to areas where plastic deformation resistance changes such as black bands on the plate caused by processing conditions, cooling water distribution, etc., and unevenness in the plate thickness is avoided even in areas where the deformation resistance changes sharply. Avoided.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing an example of a reduction motor speed control circuit used in carrying out the present invention. Fig. 2 is a signal waveform diagram supplied to each part of the circuit shown in Fig. 1, and Fig. 3 is a block diagram showing a rolling position detector and a rolling reaction force detector that supply signal output to the circuit shown in Fig. 1. It is. FIG. 4 shows characteristic curves representing plastic deformation resistance, mill rigidity, etc. L2, 6, 7, 12, 13, 21...holding circuit, 4.
9, 15... Inverter, 3.5, 10, 14, 17... Adder, 11... Divider, 18... Amplifier, 19... Multiplier, 20...
・2 interlocking volume, 22, 23...variable resistance, G
1-G16...gate, 81-S3...switch.

Claims (1)

[Claims] 1. In an automatic plate thickness control method that proportionally controls the moving speed of the reduction screw according to the size of the plate thickness error △h, find the correlation coefficient between the sequential reduction screw movement amount and the gauge meter plate thickness correction amount, The proportionality constant of the moving speed of the reduction screw to the plate thickness error Δh changes in proportion to the correlation coefficient, and when the gauge meter plate thickness correction amount becomes small with respect to the movement amount of the reduction screw, the proportional constant changes. An automatic plate thickness control method, characterized in that the constant is made small, and when the gauge meter plate thickness correction amount is equal to the reduction screw movement amount, the proportionality constant is made equal to the value.