JPS60123B2 - Successive speed control method for continuous rolling mill - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for successive speed control of a continuous rolling mill, that is, a method for controlling the speed of a plurality of rolling mills at the same time so that the interrelationship between the speeds of a plurality of rolling mills maintains a predetermined relationship, for example, the relationship of the mass flow law. The present invention relates to a successive speed control method that is effective for rolling mills in which the maximum speed of each rolling mill is limited.

Generally, the main speed control devices of a continuous rolling mill are a main speed setting device called MRH, a speed setting device for each stand called SSRH, a manual speed regulator (VRH), a looper height control device, and an inter-stand tension control device. Among these, the control for finely adjusting the speed relationship between the stands, such as the VRH looper height control device and the inter-stand tension control device, is collectively referred to as vernier speed control.

The output of these main speed control systems becomes the speed command value for each rolling mill, but the final output stage of this main speed control system has a
A maximum speed limiter is provided and functions as a limiter to prevent the speed command value output from exceeding a predetermined maximum speed. However, in this conventional configuration, when a certain rolling mill speed calculation value reaches this speed limit, it is impossible to output a rolling speed command value exceeding that limit value, and the vernier that adjusts the speed relationship between the stands becomes impossible. As a result of the inability to control the speed, there was a problem in that the inter-stand mass flow law, which is one of the basic requirements in continuous rolling, was disturbed. This point will be explained in detail below.

FIG. 1 shows an example of a seven-stand hot strip mill to which the conventional continuous rolling mill successive speed control method is applied. This is a diagram. S is a material to be rolled, such as steel, li
(i indicates the 1st to 7th stands. The same applies hereinafter) is a rolling roll, 2i is a rolling mill driving electric motor and its speed control device, 3i is a rolling machine drive system and an automatic plate thickness control device (AG
C), 4 i is looper, 5 is main speed setting device (MRH)
, 6i is each stand speed setting device (SSRH), 7i is a looper drive system and looper angle detection device, 8i is a manual speed regulator (VRH), 9i is a looper height control device,
A vernier controller that integrates stand speed adjustment devices such as AGC reduction compensation device and manual VRH. 11i is a multiplier, 12i is an adder, 13i is a maximum speed controller, and 20 collectively means a main speed control system.

The speed setting of the continuous rolling mill before the material to be rolled is reached, that is, the speed preset (initial speed cone) at the time of mill setup, can be adjusted to satisfy the following formula ○} ~ Lake by adjusting MRH5SSRH6i in Fig. 1. Calculated and controlled. The i-th stand speed is RPMi=MRH×SSRHi. …． …． {
1}ViRPMj=m mountain---------...
... [2} Force XDiX (10 fi) HixVi = constant (constant mass flow law, i = 1 to 7)
......{3} However, R edition 4i = i-th stand rotation speed MRH = main speed setting device preset value SSRHi = i-th stand SSRH preset value Vi
= I-th stand exit side plate speed Hii I-th stand exit side material target plate thickness Di = I-th stand roll diameter 10 fi = I-th stand advanced rate As the material is bitten by each rolling mill and rolling progresses, the rolled material Due to factors such as temperature fluctuations within the plate or correction of the rolling roll gap by AGC automatic plate thickness control, deviations from the mass flow rule in the example equation occur.

The vernier speed controller gi absorbs this, and as a result of manual or automatic control calculation, the speed command value for each rolling stand is determined by the vernier controller 9i and the adder 12.
i is corrected from the initial preset value of formula '1}, and the leg [6} of formula {4} below also becomes the value described here, and this value is output to the speed control device 2i to restore the mass flow law again. , controlled. RPMi=MRHXS
SRH;+{VVRi+Goi}….・．． ...{41V
i RPMiX 汀XDiX (10fi) ...,. …
．． [5) Hj x V amount = constant (i = 1 to 7)...
...... However, VvRi = i-th stand vernier control output, i = successive control output to the i-th stand, and i is the successive control output from the (i+1)-th stand to the i-th stand; i11) The amount of vernier speed correction in the stands is set to a predetermined ratio via the successive controller 10i (usually the S of the i-th and (i+1)
SRH ratio), and the i-th stand speed command value is corrected at the same time.

That is,)
(7) However, in the final output section from the master speed controller 20 to each rolling mill speed control system in FIG. 1, an overspeed limiter 13i is provided to prevent overspeed of the rolling mill drive electric motor. Therefore, the RPMi calculated by formula t4) is not allowed to be output as a speed command exceeding this overspeed limit value (of course from the viewpoint of motor protection),
Therefore, there was a drawback that the constant mass flow law of formula (2) could not be satisfied.

To explain this situation graphically, Figure 2 shows a normal rolling condition but the rolling speed initial preset value (initial speed cone) is relatively low, and Figure 3 shows a case where the speed cone is high and the vernier is relatively low. This shows a case where the speed limit is reached during the speed control process and the speed balance is disturbed. In Figures 2 to 4, the vertical axis is the speed, the machine axis is the stand number, the solid line is the maximum speed limit value, the dashed line is the initial preset value, the broken line is the corrected speed, A is the range where the limit value is output, B is the corrected speed upper limit , C indicates the lower limit of the corrected speed, D indicates the highest initial preset value, and E indicates the vernier control range. In order to solve such problems, there are methods such as the following types a and ba as countermeasures that have been adopted in the past.

a The maximum value of the initial speed cone (MRH x SSRHi) is within a certain range below the maximum speed limit (usually 95% or less)
to maintain control margin for vernier speed control.

At the same time, a limit is placed on the maximum value of vernier speed control calculation.
(Usually within 10 to 15%) b. Confirm that the maximum speed limit has been reached, and then manually or automatically lower the main speed potentiometer (MRH) by a predetermined amount.

However, as is clear from Figure 4, even this measure a does not completely solve the problem, and if the maximum value of the initial speed cone setting range is kept low, the rolling mill speed will decrease overall. As a result, the rolling function could not be fully demonstrated.

In addition, in measure b, since the speed of change of M and old H is usually quite slow, it is impossible to follow sudden speed changes due to vernier speed control, and therefore excessive distance imbalance between stands is prevented. It was ignored as something unavoidable. The present invention has been made in view of the above-mentioned problems. For example, when a request for speed correction occurs such that the calculated value of a certain stand speed exceeds the maximum speed limit value due to vernier speed control, We provide a successful speed control method that allows rolling to continue without affecting the speed balance of continuous rolling by recalculating the speed command values of rolling mills other than the relevant stand so as to quickly reduce them by the minimum required amount. This is what I am trying to do.

Now, as a result of calculating the speed command value for each rolling stand in the main speed control system 20i (Fig. 1), the speed command calculation value (value of formula Assuming the case in Fig. 13i), in this case the speed command calculation value RPMi is larger than the speed limit value RPMmax~x,i), so this RPM
The difference between m and x, 1 is easily detectable.

When the speed command calculation value for each stand mentioned above is directly outputted as a speed command value via the speed limiter 13i, due to the action of this speed limiter, only the speed command output value of the i-th stand becomes the maximum speed command value of the i-th stand. Speed limit value RPMmax,
i, which causes the speed balance between the stands before and after the j-th stand to collapse.

Therefore, to avoid this, for example, △RPMi=R
The deviation of PM amount - RPMmaxi is detected, and based on this, the speed command value for all other stands except the i-th stand is reduced by a predetermined amount, and as a result, the speed balance among all rolling stands is maintained. If the speed command value is corrected and recalculated so that the speed command value is corrected and the recalculated value is outputted as the final speed command value, rolling can be continued without any influence on the speed balance of continuous rolling. That is, the speed limit value excess amount ΔRPMi at the i-th stand is calculated and detected using the following formula.

Formula for speed command value of pond stand (younger brother i stand igoi) {
The above △RPM for RPMj, which is the calculation result of the
A correction calculation is performed based on i, but in this case, the most common way to maintain speed balance is to correct it according to the initial speed cone ratio, using the following formula: (9}.

△RPMj △RPMi SSRHi-SSRHi Geodetic RPMi=KikitomoX△RPMi(i3i).・・・
1...(9) Using this △RPMj, the speed command value of each stand is corrected as shown in the following formula (1).

RPMt=RPMj−△RPMj . ．． ．．
．． ．． ．． ■ So = RPMi - S straw calculation △RPMi However, RPMi: Calculated value RPM according to formula '4 at the j-th stand
r = recalculated speed command value of the j-th stand, this RPM
By outputting the corrected speed command value for each rolling stand, rolling can be continued without any effect on the distance balance between stands even when the maximum speed limiter is activated.

Also, if there are multiple stands that exceed the speed limit value, execute the calculation in the example formula for all relevant stand days and correct it using the maximum value of △RPMi/SSRHi output from each stand. good. That is, the formula OD. △
RPMj: SSRHiX {Maximum value of Sooke band (i Mii)}
‐‐‐‐‐‐‐‐‐‐…‐‐.

Based on the basic concept of the invention explained above, a specific example of the invention will be described in detail below with reference to FIG. In Fig. 5, S indicates a material to be rolled, such as steel, I'' is a rolling roll, 2i is a rolling mill drive electric motor and its speed control device, 3i is a rolling machine drive plate thickness control device (AGC), and 4i is a rolling machine drive electric motor and its speed control device.
is the looper, 5 is the main speed setting device (MRH), 6i is the speed setting device of each stand (SSRH), 7i is the looper drive system and looper angle detection device, 8i is the manual speed regulator (VRH), 9i is the Vernier control device, 10i is a successive controller, 14i is an inverse successive controller, 11i is a multiplier, 15iA to 15 are adders, 16i is a sign inverter, 13i is a maximum speed limiter, 20 is a master speed limiter all at once Shows the control system.

The functions and functions of li to 10i and 12i in the diagram are as follows:
It is the same as the conventional main speed control system, for example, that explained in FIG. 1, and its explanation will be omitted.

Now, suppose that as rolling progresses, the calculated speed command value of the fifth stand (F5), that is, RPM5 in equation (2), exceeds the fifth stand maximum speed limit value RPMmax, 5. Medium 155A output is RPM5,
The output of the speed limiter 135 is RPMmax, 5;
The deviation is calculated by sign inverter 165 and adder 155c.

(1 RPM50RPMmax, 5 Knee-△RPM5) This 1△RPM5 is passed through L adder 155D to F, ~F4
It is recalculated so that it is added as a successive signal of the stand, and the speed command value of the F, ~F4 stand is decreased by the value of formula (9}, that is, △RPM.~△RPM4 for each stand.Here, The successive controller 10i is assumed to be configured to calculate the SSRH ratio of the adjacent stand shown in equation (7).
M5 becomes a correction signal to the speed command value of the F6 and F7 stands via the adder 155E, the inverse successive controller 146, and the adder 156F, but the inverse successive controller 14i is located between the i-th and younger (i+1) stands. is SSRHi 11
/SSRHi is configured to perform ratio calculation, so F6,
The speed correction signal of the F7 stand also satisfies equation {9). For example, the speed correction signal ΔRPM7 at the F7 stand is
The following calculation is performed by the operation of the inverse successive controller between 5 and F6 and between F6 and F7. −△RPM7=−△
RPM 5 x Kiki Chohan x Kiki Hiru 8 Harm = -△ RPM 7 Lacquerware In this specific example, a recalculation circuit similar to that for F5 explained above is applied to all rolling stands except for pivot stand F7. Therefore, the operation of the maximum speed limiter 13i at the pond stand is similar to F5.

In addition, if speed command calculation values exceeding the maximum speed limit value occur at the same time in multiple stands, the successive circuit 1
0i, the speed command values of each stand are mutually reduced through the inverse successive circuit 14i, and as a result, only the stand with the largest relative speed overrate exceeds the limit value of the maximum speed limiter. , the function of formula tray maximum selection is carried out automatically. As is clear from the specific examples explained above, according to the method of the present invention, the mass balance between stands is always kept constant in both transient and steady state, and when the maximum speed limiter is activated, Speed correction can be performed, and it is possible to avoid negative effects such as variations in material dimensions due to mass balance disturbances associated with conventional methods.

Furthermore, according to the method of the present invention, vernier speed control that exceeds the maximum speed limit is automatically processed by correcting other stand speed command values, and there are no problems such as speed imbalance or control delay in this control. Therefore, the vernier speed control margin above the initial speed cone can be made as small as possible, and theoretically, the upper limit for selecting the initial speed cone can be raised to the maximum speed limit for each rolling mill speed. I can do it.

In addition, the deceleration correction of each rolling mill speed is always controlled so as to reduce only the minimum necessary value to maintain the mass balance of continuous rolling. This increases the speed level of the entire machine and contributes to improved productivity.

Means for realizing the method of the present invention include a known analog operational amplifier, a wired logic digital operational circuit,
Alternatively, a control computer or the like can be applied, and there is no particular problem with the means used.

Also, as a concrete time calculation expression for explaining the method of the present invention, the expression {8
) ~ However, the calculation method is not limited to this specific example, and it is possible to detect that the maximum speed limit value is exceeded and re-set the speed command value for each rolling stand without disturbing the speed balance. It can be implemented with various modifications within the scope of the gist of calculating and outputting.

Furthermore, although the final stand pivot type control system in a hot strip mill was mentioned above as an example of the main speed control system of a continuous mill, the method of the present invention can be applied to various main speed control systems of all other continuous rolling mills. It goes without saying that it is possible.

[Brief explanation of the drawing]

Figure 1 is a block diagram of a 7-stand hot strip mill to which the conventional continuous rolling mill successive speed control method is applied, and Figures 2, 3, and 4 show problems in the conventional speed control system. FIG. 5, which is an explanatory drawing for clarity, is a block diagram of a seven-stand hot strip mill showing an example of application of the present invention. In the figure, li is a rolling roll, 2i is a rolling mill driving electric motor and its speed control device, 3i is a rolling machine drive system and automatic plate thickness control device, 4i is a louver, and 5 is a main speed setting device (M
RH), 6i is each stand speed setting device (SSRH), 7
i is a looper drive system and a looper angle detection device, 8i is a manual speed regulator (VRH), 9i is a vernier controller, 1
0i is a successive controller, 11i is a multiplier, 12i is an adder, 13i is a maximum speed limiter, 14i is an inverse successive controller, 15iA to 15iF are adders, 16i is a sign inverter, 20 is a main speed control system, S indicates the material to be rolled. Note that the same reference numerals in the figures indicate the same or equivalent parts. Figure 2 Figure 3 Figure 4 Boat map Mountain boat

Claims (1)

[Claims] 1 In a continuous rolling mill where the maximum speed of each rolling mill is limited, if the speed command value of the rolling mill calculated according to the rolling condition exceeds the maximum speed value, the speed command value and the maximum speed A method for successive speed control of a continuous rolling mill, characterized in that a comparison value with a speed value is derived, and a speed command value to other stands is lowered based on this comparison value.