DE1956746A1 - Device for regulating the thickness of rolling stock - Google Patents

Description

: L3CT? .IO CORPORATION Erlangen, the

ittaburgh, Pa., USA Werner-von-Siemer.s-S ^ r “50

Sign:
VPA 69 / 32-32 Hk / Xs

Device for regulating the thickness of rolling stock

The priority of the corresponding US application dated 12.11.1968, File number Serial Ho. 774 · 638 is being claimed.

The present invention relates to a device for regulation The thickness of the rolled stock in a rolling mill is the at least one whale stand with a control device for the adjustment of the roll gap contains, with sensors for recording the rolling force and the adjustment position, with a device for determining the rolling force error from the measured rolling force and a rolling force setpoint and from the respective actual value and a specified one Setpoint of the position and with a device for determination the size of the pitch movement required to correct the thickness error.

Operationally, the unloaded roll gap and the speed on each stand of a tandem train or for each pass of a reversing train are set by the operator or a computer in order to achieve a step-by-step reduction of the rolling stock to the desired final thickness. In general, the loaded roll gap on a roll stand is the same as the initial thickness of the rolling stock under the normally applicable condition that there is little or no elastic recovery. Since the conditions for the adjustment can be wrong and in each case certain rolling parameters during the rolling and after the adjustment on the loaded roll gap
act, a thickness control system must be used to precisely maintain the desired final thickness, e.g. for a frame on a reversing line or for selected roasting systems on a tandem line.

The known method for thickness control via the rolling force

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is used in particular in steel strip hot rolling mills and in heavy plate reverse rolling mills used. The theory on which the procedure for thickness control based on the rolling force is described, for example, in US Pat. No. 2,726,541.

In this process, Hooke's law is used to regulate the setting position at.einem roll stand, ie the loaded roll gap is the same during a rolling process
unloaded roll gap (the adjustment position) plus the spring-back of the stand, which is caused by the separating force exerted by the rolling stock on the rolls. To implement this principle, a rolling force measuring device measures the separating force and the setting position is controlled in such a way that the changes in the rolling force related to a reference value are compensated for and the loaded roll gap is kept at an essentially constant value. The following formula shows the basic relationship:

(D h = s _{o +} 4-

In it is:

h = loaded roll gap (thickness of the outgoing rolling stock) S = unloaded roll gap (pitch position)

K = spring constant of the roll stand

F = separation force.

Depending on the rolling force, the setting position is regulated according to the following equation:

(2) AS = - ΔL

In it is:

Δ, F = measured deviation of the rolling force from a reference value AS = controlled deviation of the adjustment position from a reference value of the adjustment.

By fulfilling equation 2 and the requirements according to
Equation 1, the loaded roll gap h in Equation 1 is kept at least approximately constant.

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As this device for thickness control without measuring the actual Thickness is working at the exit of the stand, adjustment of the adjustment is necessary during the rolling operation, to correct the normal thickness errors due to various causes. With re-enactment is here the change in the setting position to correct a thickness error referred to by a single rolling parameter or caused by the combination of rolling parameters or is caused as expected and which cannot be compensated for by the control device alone. As a normal mistake are the errors identified by simple adjustment the employment can be corrected. Such normal errors are, for example, inaccurate setting, automatic adjustment adjustment, a change in the spring constant of the roll stand, temperature changes and changes in the rolling speed.

To correct such normal errors, a known Diokenmeßeinrichtung for readjustment of the pitch position is normally used at one or more points, usually arranged on the outlet side of the rolling mill. It measures the thickness with time Delay towards the point of origin. Sin surveillance system compares the actual with the desired thickness and adjusts the control device on one or more Scaffolding the road.

The thickness control must be carried out quickly, since a relatively short delay leads to a considerable length incorrect thickness of the rolled material. In tandem mills in particular, the thickness accuracy of the outgoing line depends Band depends significantly on the control speed and the stability of the control device, because these factors affect the Determine the length of the band with a thickness defect.

The control speed depends above all on the ratio of the pitch movement to the rolling force error detected in each case (or to another input error). Since the thickness of the rolled material at the exit of a stand through the intersection of the curve of the spring constant (rolling force across the roll gap) with the curve of

Rolling stock de format ion (rolling force via decrease in thickness) is determined, depends on the total amount of the correction of a rolling force. Fehlerα or some other detected error primarily from the spring rate of the roll stand and the plasticity of the rolling stock. The term "rolling stock plasticity" as used herein is intended to mean the deviation of the rolling force based on the deformation or decrease curve. From this definition it follows that the workpiece width influences the plasticity, because the rolling force required for the respective decrease depends on the workpiece width depends.

If the control device is not properly coordinated, excessive damping of the adjustment with too long a correction time or undamped, overswing or jerky cork rectification movements and, in some cases, an unstable course of the adjustment movement can result. Optimal control behavior requires critical damping and generates the fastest, stable and non-overshooting adjustment movement that can be achieved with analog control via the rolling force. Changes in the plasticity of the rolling stock, which are based on the cold spots caused by the slide rails or other factors, can produce changes in the control behavior of more than 10 fo .

The curve of the framework spring constant is usually considered to be constant and uniformly extending line and is therefore generally referred to as the spring line. Indeed it is however, this curve is not linear in the area of small rolling forces. The linear part of the course of the spring constant is also changes subjected during the rolling process. The linear part can be changed by one or more changes Parameters, including the diameter of the backup rolls and the width of the rolled stock, may change by + .10 '$. Since the rolled stock width and the diameter of the support rollers are known values or are determined at the beginning of a stitch and normally do not change during the stitch, they usually call no changes in the spring rate during operation. Changes in slope in the linear part of the curve however, the spring constant can be caused by other variables. Changes in the spring constant can also immediately. Thickness errors cause »those caused by a

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Re-adjustment of employment can be corrected »

Plasticity fluctuations are probably the most important operational cause for changes in the control behavior. The steepness of the deformation curve, i.e. the plasticity, depends on the width of the rolling stock and also on the thickness and the temperature of the rolling stock. So is the type of material decisive for the plasticity and slight differences in the material composition can mean differences between the estimated and the actual plasticity.

To improve the thickness of the one coming out of a rolling train Rolled stock includes the device for determining the pitch movement, a device that provides the correction variable for the pitch movement in accordance with a relationship between the values for the plasticity of the rolling stock and the stator elongation constant continuously operationally ir dependent on the determined by a change in the position of the rolling force and influences the regulation of the position.

The invention is explained in more detail below using an exemplary embodiment shown in the drawing? show it:

Pig. 1 a schematic. Representation of a control device for a tandem mill,

Fig. 2 the elongation characteristics of a roll stand, Pig. 3 and 4 each part of a thickness control program.

In Pig. 1 shows a tandem mill 10 which comprises, for example, seven roll stands, of which, however, only stands S1 and SS are shown. The rolling stock passing through the tandem train is rolled into a strip and wound onto a reel 16 at the end of the train. The incoming rolling stock, for example steel, has, for example, a thickness of approximately 2.5 cm and a width in a range from approximately 50 to 200 cm. The strip exiting the roller train has approximately the same width and a thickness corresponding to the respective order. In each roll stand, the rolling stock passes through a pair of work rolls 22 and 24, the speed of which is controlled by a direct current drive motor. For setting the unloaded roll gap

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ar. each stand is a pair of Anatellrnotoreri? ⁿ and o ir. A pair of spindles 30 are provided which engage the support rollers and thereby exert pressure on the work rolls. By means of a sensor 32, the spindle position is detected on each frame and converted into an electrical signal. The precise alignment between the spindle position and the unloaded roll gap can be checked and corrected from time to time by a monitoring device. A pressure measuring cell 34 is assigned to each roll stand that is equipped with a thickness control device. Often the other roll stands are also equipped with pressure cells. In the present case, all seven roll stands are equipped with a thickness control device,

At predetermined points along the Walisenstrasse, motor-driven guide rollers 36 are arranged to guide the rolling stock laterally. A provided for the automatic operation of the tandem mill control device 12 comprises a digitally operating computer 33, which with. is connected to the various sensors and control devices of the rolling mill. To carry out certain rolling processes, the control device 12 can contain a conventional analog control which can be operated manually or automatically. The computer 33 advantageously consists of several separate computer units, for example one computer unit each for the adjustment, for the roughing train, for the finishing train and for the thickness control device in the trunk train. The computer units are linked to one another to integrate the rolling process. For example, the inputs of the computer unit for employment are connected to the different sensors, while the outputs are connected to the other computer units of the computer 38. Each computer contains an input part, which in turn contains a device for querying switch positions or signals representing the current status of the rolling process, digital-to-analog converters and a device 40 for inputting information, for example via punched tapes, teleprinters or dials. For example, the desired final thickness and temperature of the strip, the initial thickness and width of the strip, the quality of the steel to be rolled _t, selected plasticity values and control programs are input via the device 40.

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The inputs of the computer unit for the automatic thickness control the following signals are supplied:

1. one proportional to the separation force at each roll stand, of the rolling force signal detected by the measuring cell 34,

2. the signals generated by the sensors 32 on each ^J roll stand, corresponding to the spindle position,

3. the signals recorded by tacho generators 29 at each stand and proportional to the pitch speed,

4. the position signals emitted by rollers 41,

5. the output from tacho generators on the rollers 41, signals proportional to the rolling speed at each stand,

6. a thickness error signal from an X-ray thickness gauge 42 located at the exit end of the road;

7. one proportional to the temperature of the incoming rolling stock, signal generated by a sensor 44 ″, which may only be is removed from the first incoming rolling stock H and stored, while a change in employment for each subsequent rolling stock is only changed if its temperature deviates from the stored value,

8. Signals corresponding to the width, coming from with the lateral Guide rollers connected potentiometers are generated.

The rolling force measured at the tip of each strip is stored and used as a reference value for the thickness control device on the corresponding roll stands, if the computer unit for the thickness control device works in locking mode. If, on the other hand, this computer unit works in normal operation, the computer calculates for the adjustment the rolling force to be specified for the rolling stock tip, which is used as an absolute reference value for the thickness control device is used.

Signals derived from the rolling process and the signals given by the operating personnel from a control panel 43 are sent to the computer for thickness control via the input channels fed.

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Each computer unit of the digital 3.echr.ers ". S: ^r: ': no ^r": "l' ^iT 'w <- o nit its own output part equipped l ^rn the present case, output parts of the main computer unit... (Computer unit for the PertigstraSe), the computer unit for the Terptraie and the computer unit for the Diclcenregulation are connected. Various control devices are operated via the output channels depending on the control commands calculated or set in the computer on the basis of the control program. The devices are either directly controlled via the output part or via digital-analogue TJ ^ eotzer bet -'- '. The main outputs of the computer for the thickness control ^ üh-on commands sent to the respective control units 48 for di ⁿ division k are fed via the motors 28, and speed preset signals, which are fed to the control devices for the tension sensor for changing the drive speed, in order to adjust the belt tension to compensate if? ioh the band diok ·: changes as a result of an asylum movement.

At further outputs of the computer 38 are display and printing devices 46, for example digit displays, punched tapes or teletyping machines, connected, then the operating personnel is informed about the Waiz operation and incidents attention is drawn, which make intervention necessary. The printing devices are used to lower the '.Valzdat ^ according to the monitoring program set in the computer ) used. . .. ■

With each computer unit there is also an external direction connected, which feeds a sub-tripping signal to the computer, when an input signal is available or when the transmission of an output signal is completed. The main ranger is working generally due to the interruption signals in According to a common program that is part of a program system and the main computer for a periodic or other control action or for other programs. In some cases, individual interrupt signals are recorded and triggered without priority restrictions.

The connection lines indicated in the drawing. between the computer 38 and the individual for the.WaIr-Vr "!"

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The connections between the captain's unit and the rolling mill as well as the connections between the computer unit for the thickness control and the rolling mill represent the most important aspect. For example, the initial settings. the spindle positions on the individual stands can be brought about by the main computer unit via the "computer unit for thickness control and the devices 4.8 for the adjustment Walzgeschwind it igke and set the tape tension controlling device 50 in the same manner the guide rollers;.. 5o controlled by cli ^ main computer unit, the velocity distribution during a rolling period, ie, the acceleration, maintaining a substantially constant Walsgesichwindigkeit, and the delay are also controlled by the chewing unit via the control devices 50.

The mentioned sub-operations' in the roughing train and the computer unit for the commissioning ensure both the commissioning and the logical process for orphan slabs in the roughing train as well as for controlling others with the entry of slabs into the roughing train and for the transport of the rolled stock to the finishing train. the The computer unit for commissioning calculates the rolling plan for the roughing train, and that of the computer unit for the roughing train is used to commission the roughing train.

The computer unit for commissioning calculates the required course of the rolling speed and the rolling plan, the spindle position, the values for the speed and the strip tension for each roll stand of the finishing train. The main computer unit determines the start-up and the consequent activation of the drives of the finishing train and the other devices required to initiate the rolling process. The model equations used in the program for the finishing train ensure better thickness control at the tip of the rolling stock on the basis of the results obtained from previous rolling processes Results »The other work processes in the finishing train, such as ignition, spraying of the rolling stock and rolling mills, are also controlled by the main computer

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'The computer unit for the thickness control uses the Hooke's law to determine the total amount of the adjustment movement to set the roll gap to the desired value and to achieve the desired thickness of the rolling stock coming out of the respective roll stand. The pre-calculation determines the total change in the unloaded walnut that is required to set a rolling force for a new whaling process or other rolling forces to compensate for a thickness error. The precalculated change in the spindle position is used in the thickness control program of the computer unit for the thickness control in order to determine the timing of the pitch movement to P.

Since the Gesamtanstellbewegung is set, the correction of the setting position with the optimum or approximately optimum time course, depends on the accuracy of the calculated adjustment movement can be carried out. Its faster working thickness control reduces the amount of readjustments of the. Employment due to transport delays, falling temperatures or other ramp-like * conditions. Such conditions tend to turn an inherently short-term thickness defect into a permanent thickness defect.

. The thickness control device according to the invention comprises the control the rolling force on each individual stand and a control of the adjustment. The employment tax system preferably includes a control circuit which operates in response to the thickness gauge 42. -.

At the beginning of a rolling process, the computer generates output signals which are fed to the control units 48. Using the Adjusting motors 28 and the spindles 30 are used to set the desired unloaded roll gap on the roll stands ..: At the same time, the computer controls the rolling speed, des respective rolling frame and the strip tension between, the frames. As usual, the output values are based on the data of the Rolling mill incoming Barrens (width,; thickness and femperafcur) ^ on the desired properties of the outgoing belt *

bad original " ^{1 T} "

the stitch program _{5 is} based on the information etc. recorded in a previous thread.

The computer solves the required at the beginning of the rolling process Processes in the street. After completing a 7 / alz process the conditions for the next bar are calculated- and hired new jobs.

In order to achieve an on-line thickness control, the programmed thickness control device works both in dependence. the signals of the setting position sensor and the Druckmei2 ' ³ lle ^ d ⁿ s roll stand, as well as depending on ve η the error rate.' ⁵ ! de? Thickness gauge. For this purpose, the computer; 3 is also supplied with the speed of the adjusting motor for controlling the adjustment. The die control program includes programs for controlling the computer itself and for issuing the control commands.

The curves shown in Fig. 2 illustrate the application des Hooke 'see G-esetzes at a roll stand and the basic position, on which the thickness control device improves the rolling speed, which provides accuracy and stability and other advantages. Lay curve 52 of the scaffold spring-up Distance between the work rolls as a puncture of the separating force (?) and employment (S) firmly. The slope of the scaffold suspension curve 52 represents the Peder constant K, which, as already described, is subject to fluctuations. The zero position the employment is due to the position of the people who are in contact with each other Work rolls determined. The curve of the spring constant corresponding to the zero position is indicated by the reference symbol 52-0 marked. Under the condition of perfect calibration, this contact occurs when the employment is due to the non-linearity of the lower part of the rebound curve has a slightly negative value.

In the case of an unloaded, "larger" YJaltspalt shifts the spring-up curve to the right, as for a roll gap S indicated by the curve marked 52-S. In the same Way, the curve shifts to "lefty" when the roll gap from this position it is reduced in size; I every hiring

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η is the thickness of the expiring whale - "good gle

unloaded roll gap marked by the setting position S pe plus the frame expansion caused by the rolling stock. If the position is not perfect, ie if the actual zero position deviates due to wear and tear of the roll curvature or for other reasons from the theoretical position, then the thickness of the rolling stock running out is equal to the unloaded one Roll gap + Gorvsi elongation + calibration s error .--

The amount of stand spring-back depends on the characteristics of the thickness decrease curve of the rolled stock. The curve 54 shown in FIG. 2 represents, for a strip with a predetermined width, the amount of the rolling force that is required to reduce the rolling stock entering a rolling stand. The plasticity P of the rolling stock is given by the slope of the curve '54. In the present case, curve 5 ^ is shown as a straight line, although there is normally a slight non-linearity. The desired rolling stock thickness K corresponds to the initial value IC generated in this case, since the amount of the _{rolling force required for reducing the rolling stock thickness before H. ,, T} to H is equal to the amount of the separating force caused by the loaded roll gap H, ie the point of intersection of the Springback curve 52-S _1n for an initial _{roll gap S 1n} with the decrease curve 54 represents the desired thickness value.

If the thickness of the rolling stock leaving a rolling stand increases from size GE to H "during a pass due to an error and thus corresponds to the actual value PC - in this example because the plasticity of the rolling stock increases and the thickness of the rolling stock increases to H. _v " _v changes, wi · ^ represented by the curve 53 - the roll gap must be reduced to a value which corresponds to a future value FC. The point of intersection of the spring-back curve lies at the value FC. with the new decrease curve 58 at the desired value H and accordingly the spring-back curve 60 now applies. In other words, the adjustment correction causes the unloaded roll gap to be reduced by an amount Λ Sp ^ to "Innn neuon Wort, which, taking into account the neut ^; n scaffolding

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is equal to the desired thickness H.

The amount & S _R j> is predicted according to the following equations

_R j>

calculated:

In it is:

PS =

PE = required

Employment correction.

K = framework spring constant (10 kp / cm) P = plasticity (1O ⁶ kp / cm)

Equation (3) results in Yerlsiridui.g with Pig 4

= Thickness error

(5) Δψ = P · GE = change in rolling force due to adjustment of the pitch

= P · GE

^{1 +}

PE

To calculate the amount to correct a rolling force error required pitch movement, the rolling force error PS is calculated as follows:

(β) FE =

- P _R - K {

To calculate the rolling force range, the difference is according to equation (B); between the actual value F ^, and the reference value F _{R of} the WaIzgeblld-et and γ © ϊΐ this © ifferen? The amount of the .d

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the change in position caused by the change of position is deducted. The one calculated by applying the equation (8) "
Rolling force error is equal to the amount by which the measured rolling force differs from the rolling force required for an error correction in the respective setting. For the funct PC in Fig. 2, in equation (8) S _Q = S ₁₀ , however
S can of course take on any other value.

A pitch correction by the predetermined amount produces a change in the rolling force and FS becomes zero if during
the duration of a correction no new rolling force arises. If FS is not Mull, then a new rolling force error will distort to the extent that a pitching movement by the previously calculated amount cannot correct the pitch error in the rolling stock exiting the roll stand.

The in 'equation (8) as a starting point for the determination of the rolling force error

follows togetherί

Rolling force error FE adjustment value S _{1 used} is set like

(9) S ₁₀ (new) -S ^ - S _{M +}

In it is;

S .. '= ViO in the piekenmeßgerät influenced setting value

= for the thickness correction during acceleration
■ or deceleration of the rolling mill with specified pitch

= Employment due to an advance compensation of a
Rolling force error

The reference value S ₁ . the adjustment is formed according to equation (B) when changes in the adjustment values S ,,, S _CE t and S-npp occur
Employment, on a correction of the Dieken error on the rolling stock tip iaei v <ef riegel tem computer, on a TorauskpffipeRLga ^ ti © n © toes falzfeaffefehlers. more often others fail · ibei? i! 43i @ n. »

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If a Dxck-enmeiigerat and a correction based on the course of the rolling stock speed or the rolling force are not used, the corresponding values S ₁ ^, - S _C3L , S ^ p in equation (9) do not apply.

By specifying and utilizing the total amount for correction of rolling force errors according to equation (3) Adjustment movement, the control device is adjusted electrically and characterized by a behavior that enables a Carry out control with critical or almost critical damping and thus greater stability than earlier under dynamic operating conditions was possible. The calculator can essentially provide the critical attenuation for employment as a a puncture of the amount of the pre-calculated pitch movement on the basis of the automatically determined rolling stock plasticity determine at each individual stand and at each point in time,

One factor that can limit the attainment of critical damping and one hundred percent outflow is that Accuracy with which the calculations for the corrective movement of the adjustment with the actual, for the correction of a Thickness error required movement corresponds. The precision the calculation depends on the accuracy with which the operating values of K and F are predicted can.

In general, the value of each framework spring constant K is relative exactly known. It is first determined by the usual employment test and on the basis of each trick the width of the rolling stock and the diameter of the backup rolls are calculated. Each curve 52 of the framework suspension is for the On-line thickness control saved. The type of storage can be different. In the present case - the slope of the linear part of the curve is saved as a single value. The non-linear part of the curve is made more different by three lines Modeled slope, the slopes of which are stored as three constant values and used when the roll stand is operated in the area of the corresponding rolling forces.

BATHROOM OFFICIAL

Data evaluated by the computer show previously unknown relationships with which changes in the framework spring constant can be determined as punctures of rolling parameters . From this, on-line calculations of the spring constants can be programmed in accordance with such relationships under dynamic operating conditions.

According to the invention, the operating value of the plasticity P at each stand is automatically determined with higher accuracy through calculations, determined, based on the measurements on the, -related Establish a stand. These measurements include the rolling force and the setting position on the roll stand for which the plasticity should be calculated. To calculate the plasticity on a. Roll stand N the following relationship is used:

(10) P (N) =

DS (N) / DF (N) - 1 / K (N)

In it is:

K (N) = Peder's constant for the rolling stand N

DS (N) = change in employment from reference value of employment on scaffold N

DP (N) = change in the rolling force on roll stand F due to eivr Change of employment

Equation (10) is derived trigonometrically from the working curves of Figure 2. For example, the triangle A, PC, PC can be used to derive P (N) and in this case DP (N) = F ^ - Ρ _χ and DS (N) = equal to the positional difference between PC and A. To obtain a In the present case, coordinated thickness control is provided with a thickness measuring device as well as an advance consideration of the acceleration or deceleration of the rolling speed and an advance correction of the rolling force error. The following equation is used for this:

• (11) Δ5 = As _{R ¥} - s _M + s _CSL + s _{H? P}

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When a thickness gauge is not used and the course of the speed and the rolling force is not taken into account, the last three variables are omitted. Each correction depends on whether the respective thickness error is equal to or greater than a minimum value characteristic of the respective roll stand, and also from. one characteristic for the respective stand, predetermined relationship.

The correction to each depending on the rolling speed In this case, the stand is set to the amount of the rolling speed programmed in the computer to regulate the outlet temperature the belt or productivity. The time of the correction in relation to the respective time of the Speed changes are programmed. By taking into account in advance of acceleration and deceleration is that Thickness monitoring device 42 relieved.

The advance correction of rolling force errors is provided on predetermined whale stands on the basis of the rolling force measured on one or more preceding rolling stands. The correction of the rolling force on each Wals stand is defined in the thickness control program, taking transport times and the size of the previous rolling force errors into account. The main advantage of correcting a rolling force error in advance is that the pitch on one roll stand can be changed to compensate for a rolling force error found on a previous stand. In this way, in particular, the cold spots originating from slide rails can be better taken into account. To a certain extent, the readjustment of the adjustment required due to the transport time and the output of signals from the monitoring device can also be restricted because the rolling force responds more quickly. control of tunnels with falling temperature and other ramp-like conditions can be better recorded. ₀

The programming device for the thickness control includes an analog interrogation device "which can interrogate, for example, 30 points per S ^ '- undo". ^: · -.Αη- ^: 11 «·· can, for example, lead to about 0.2 3" cd ■ „■ ro -ψ ι within τοη.

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In the present case, the program contains two levels of legality, a main plane and a jieb plane, one of which, however only the secondary level is used. Either of these two priority levels can have a number of sub-levels. In addition, alarm processes run outside of the priority sprograiom. Each sub-level can assume five operating states:

1. Requirement

2. Operation

3. Time delay

4. Interruption

5. Rest.

When a program runs on love priority it can not be interrupted by another program of a sub-level, but by an alarm process or possibly through an operation on the main level. When a program uses the If the sub-level goes into the delay, interruption or idle state, the priority program selects the highest priority sub-level that is in the "Request" operating state and moves it this in the "Operation" state. In an application according to the invention The following priority sub-levels were intended for the Dikken regulation:

(15) Tax program for employment

(H) Start-stop command for employment

(13) Decoding - for translation into and out of computer languages

(12) Thickness control program

(11) Programs for various operating functions (10) Display and zero errors for the operating personnel (9) (not used)
(8) Thickness control program X for the infeed controlled from the desk, for the implementation and maintenance of

Adjustments
(7) Control panel * for entering programs or making changes

of the program and individual seeds (6) Threading for the pitch control - commissioning of the Batenbuffer and Zenji? «Icheii-3iti3 for jeatü band imd loading

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calculation of the spring constant and other parameters, which are dependent on the bandwidth and other characteristic inlet values

(5) (not used)

(4) Adjustment of the position sensor

(3) Record, for the error printout program

(2) Determination of the course of the pitch movement

(1) Log of error messages and alarm inputs

The thickness control program includes a subroutine for precalculated course of the rolling force error, a sub-program for readjusting the adjustment and a sub-program for the advance consideration of the increase and decrease of the rolling speed. The program for regulating the pitch works depending on one of the thickness regulating program certain starting point.

In this case, the subroutine for readjusting the adjustment is carried out approximately every 0.2 seconds after each measurement of the thickness error executed. It has the following functions:

(1) Check the selector switch and the permitted combinations

(2) Checking the deviations of the measured error from given limits

(3) Calculation of the value S «for each regulated roll stand

(4) Determination of the time intervals between the correction specifications for every roll stand

(5) Consideration of the manually specified parameters

(6) Storage of the thickness error at the tip of the rolling stock for adjustment at the end of the strip when the computer is out of order is

(7) Calculation of the correction quantity Sq-vt, for the adjustment to compensate for the effects caused by the belt acceleration or deceleration

(8) Calculation of the rolling force to be specified S ™ Bäumen on the roller

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stand S2 to S7 from the course of the rolling force on the previous one Roll stand or from a predetermined course of the rolling force

(9) Calculation of the size of the compensation for the tension-free "End of tape.

The program-based check of the selector switch and the permitted combinations is carried out before the calculation of the values dependent on the monitoring devices. Adjustment of the adjustment is only possible if a main selector switch for the thickness control is set to the "Monitor" position and if a switch sensitive to X-rays and a selector switch for thickness measurement are in a position other than the "Off" position. Furthermore, the measured thickness must be exactly as great as the thickness specified at the infeed of this strip and the signal proportional to the measured thickness value must lie within the programmed limit values. Another important compensation value is the time it takes for the tape to reach the Δ-2 thickness gauge.

The error signal of the thickness measurement is first converted into a digital quantity before it reaches the permissible limit values is checked. A positive error signal corresponds to a too large and a negative signal to a too small thickness. The signal proportional to the absolute size of the thickness error is compared with a predetermined limit value and, if the error is greater than this value, no correction is made made because it can be assumed that either the thickness was read incorrectly or that the pitch was set extremely incorrectly became. In this case, the operating personnel can press a push button, whereby the incorrect thickness value as The new initial value is saved and the calculation is compensated for in the thickness control program with this new value will.

The size S _M is calculated for each individual roll stand using the following formula:

(1.2) S _M = M ₁ · XD + M ₂ · j TQ · dt

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In it is:

M-, = "constant of proportionality for the respective roll stand ·

Mp = constant of integration of the individual roll stand

XD = thickness error

The integral variable is checked for specified limit values so that this variable does not build up during longer error periods and a quick evaluation is made possible if the error changes its sign. The calculated value S _M for each roll stand is also checked for predetermined limit values and stored for use in the thickness control program.

A tolerance band for the measured thickness value is specified for each roll stand. The tolerance band causes the thickness gauge triggered corrections for small thickness gauges on the two or three last stands are executed, while larger errors cause a correction to previous stands.

To maintain the stability of the control device, successive control interventions must be carried out on each roll stand greater time interval than the running time of the strip from the respective stand to the thickness measuring device 42 is equivalent to. To calculate the control intervention for each roll stand, one is preferably specified for each stand Model size is used so that the control interventions on each framework coincides with the respective corresponding runtime. the The model size for each roll stand is preferably via the bundle threading program adjustable within the stability limits of the control device.

The time interval for entering the model parameters, which are used for the successive calculations on each individual roll stand, can be adjusted via the program for the adjustment of the adjustment depending on the thickness adjustment band. For example, the Diofcen Fehlerr'i'mal all '} (;, 2 eec is entered, but the pen learning signal ar ^ in ^ m <~ or £ ~ ^r if? Nüvn <} n. Walsgerüst na eh, jo oinor "Sokun 'ie one

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are given. Then every fifth thickness error signal would be used for the calculations on this stand; if but the thickness error is in the tolerance band, i.e. there is no control intervention necessary, then the number of entries is set to a higher value, for example to the number with which the thickness errors are read off, i.e. every 0.2 seconds, In this way, inputs for correcting the thickness of the development of a thickness error outside the tolerance band can be made more quickly follow. This works with the withdrawal of the control intervention System again with its normal query time.

To calculate the amount required for an acceleration or deceleration Correction determines the subroutine for the post

|, position of employment, for example, the difference between the rolling stock speed and the threading speed on the roll stand S6 and, during acceleration, performs a all rolling stands common, the roll gap enlarging correction, which multiplies equal to a given constant with this difference, and during a delay a correction common to all stands in the sense of a roll gap reduction, where the correction variable is equal to a constant multiplied by the difference. The advance corrections of the rolling force are based on the rolling force curve on a preceding roll stand and are made taking into account the Running time of the rolling stock executed. The specification of the pitch movement S-njvp due to the rolling force variation is as follows

* calculated;

(13) S _RFp = C · 0ΡΕ) _ρ

In it is:

(FE) p = rolling force error for specification

C = predetermined constant for each roll stand, which is in a balanced relationship to the value (FE5 _p for the following roll stand; the constant is partially 3 derived from the value L in equation (3) on one of the roll stands or - if necessary on roll stand 1 ₃ \.

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In the sub-program for the adjustment of the employment are those Calculations for the compensation at the end of the rolling stock in exact accordance with the specified large or small compensation values carried out.

The thickness control program runs periodically for each rolling stand the road and according to the program the respective pitch movements are calculated that are necessary for maintaining the thickness between the individual roll stands are required, and an improved uniformity of the outgoing strip and cause improved accuracy of the desired thickness. The rolling force values detected by the pressure measuring cells 34 are entered into the thickness control calculator and the changes in the output thickness at each stand are applied of HookeV's law and in particular by using equation (8) from the rolling force changes. The change in pitch required to correct a rolling force error is calculated in advance using equations (7) and (10) and the total change in pitch calculated according to Equation 14 includes that for the correction the rolling force error required change of the position and the possibly necessary readjustment of the position.

The following run purely for the implementation of the thickness control program Basic functions from:

(1) Checking the strip in the respective regulated rolling stand and the neighboring rolling stands

(2) Review of the data provided by the operating staff and the allowable compensations

(3) Entry of a reference value for the rolling force or acceptance of the absolute rolling force setpoint given by the computer

(4) Determination of the rolling force changes and calculation of the plasticity of the rolling stock and the correction changes of the employment

(5) Calculation of a reference value for employment for the regulated

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regulated roll stand by combining the previous setpoint for the adjustment with the 'calculated under point 4 Changes in employment to compensate for a rolling force error, also to compensate for a thickness error in the subroutine for the guard position of the employment, the specified acceleration, the tensile stress at the end of the rolling stock and the rolling force curve to be specified

(6) storage of the optionally by hand commands and resetting of the position at the end aes tape, if this is not controlled by the computer

(7) Retrieve * the program for the recruitment of the employment

The thickness control program checks before "defining" the control interventions a number of tasks to be carried out by the company staff Actions and the operating status of the system Switches. The more important check-ons are:

(1) the main selector switch for "thickness control must not to be on "Off"

(2) the selector switch for the thickness control of the controlled The roll stand must not be in the "Off" position

(3) the signal "strip in the roll stand" must have been picked up

(4) the signal "tape in the following state" plus a short one Delay duration · must have been recorded

(5) the employment must be switched to "Automatic".

If one of the required preselected or permissible. conditions is not fulfilled, the control loop for the roll stand under program control is out of operation and the rolling force error and the adjustment corrections are ineffective for this status.

The basic logical steps for determining the sequence according to the thickness control program are shown in FIG. 3 and Fig. 4 is shown. In general, equation (3) is used and the plasticity of the rolled stock is determined by applying the Equation (10) is determined.

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After triggering a start command _: and checking the correctness for the regulation on a rolling stand, the rolling force error, as indicated by reference numeral 70, is calculated. If the calculated rolling force error is smaller than a predetermined maximum value, it is multiplied by the quantity L, as indicated by the reference numeral 72, to specify a change in the pitch required to compensate for the rolling force error. The improved, automatic determination of the G-size L lays the foundation for an improved behavior of the thickness control device. To determine the pitch correction in advance, the value of L is calculated from the plasticity of the rolling stock P and the spring constant K. The plasticity of the workpiece is automatically determined for each regulated roll stand for use in block 72 via the length of the rolled stock, as shown in detail in the block diagram 75 of FIG. The plasticity value for the threading is determined for each stand and stored for totalization. The input 75 is carried out simultaneously with the thickness control program and the calculation of L and / \ S _R -n to determine the control input for the adjustment of each regulated rolling stand.

After the input, the change in the setting position DS in block 77 for the roll stand (N) is determined by the plasticity is to be calculated. This change in position is equal to the difference between the respective actual value (Sp (N) and the setpoint of the Adjustment position S ^ / "\, which in turn is the last adjustment position at which the plasticity of the rolled stock was calculated. In the same way, the rolling force DF (N) in block 79 is off the difference between the current actual value of the rolling force Fpfjj) and that reference value SVww) determined by the appointment of the position S-o / ^ n consisted of ..

If the change in position is less than a predetermined amount, preferably 0.01 mm, the block 81 ends the input step. The present WnTt. the plasticity P- (JJ) -for the regulated roll stand v / ird without .summing up to. to the next writing of the Bickenregalurirsprograirnn for the same 3t'i? v ^,! _f '' o: .u: oioh i ^ t. This mer-icmal accordingly determines a ri ^ n 3ο ^> -Λ ¥ - '*': _ ΐ7 / ί'.Γΐ J-ir or required cm- PoRitiorioäncierun ^ before a

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Summing up the plasticity values is permitted. Incorrectly determined small changes in position can - therefore no change of the stored plasticity values, yet the threshold is low enough to allow a quick summation to allow the rolling force changes rather than decreasing temperature or other effects related to the changes brings the employment position. Furthermore, a low threshold and a fast summation make the utilization relative small portions of the curve of the spring constant and the rolling stock deformation and therefore reduces the effects an error caused by the non-linearity of these curves can be evoked.

If the pitch movement DS (IT) is greater than 0.01 ram, conducts block 81 the input to block 83 if the plasticity P (N) has been calculated using equation (10), block 85 stores the value P (N) and passes the sum block program

The input block diagram 75 can be used in tandem or reversing rolling mills for threading and offsetting. Furthermore, predetermined values for P can be used from the control panel for threading and automatic continuation in accordance with the block diagram 75 . As a further possible modification, P can correspond to that described here. The calculation method determines SöEX and is used, but only if the size is within specified limits, or values specified by the control panel or saved in another way can be used if the size is outside the limits.

In some cases it may be desirable to perform the calculations of the quantity P on a different 3-round basis than the periodic execution used in the thickness control program .

The calculation of the share of reging or change in position to compensate for whale force causes a pre-load correction. The calculation of the rolling force will fail in 31ock 70

■ .-; :., '■; ■■ - 27 -

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used to repeat the correction due to a to avoid positive rolling force signal, as in connection with the explanation of equation (9). If a given If a change in the working position does not correct a rolling force error as intended, a small rolling force error remains exist, which is then treated as a new rolling force error. In practice, the analog scanning speed can be faster than the speed at which the pitch motion to compensate for at least some or perhaps most of the rolling force errors can be carried out, and the rolling force error calculated in each case in block 70 can be performed at a specific point in time a part of a previously uncorrected rolling force error, a new rolling force error or one after the pitch movement contain residual errors due to an imprecise forecast, or a combination of these errors.

In order to determine an overall change in the adjustment position required for the regulation, this change calculated for the adjustment of the adjustment is linked to the variable ASp, as indicated in block 74. The total change AB of the employment position is checked whether it is within the limits, and furthermore, as indicated in block 80, added to the previous setting of the employment position for further coordination so that the new setting of the position as indicated in block 76 results. The new setting of the pitch position is used in the pitch program, as indicated in block 78.

At the point in time at which the end of the rolling stock 14 passes through each roll stand, the compensation value is added to / \ ß in block 80 to achieve the correct change in the position. The calculated setting point for the contact position is checked whether it is within the limits, as indicated in block 82, before it is called up from the program.

After the thickness control program has been executed for the roll stand that has passed through, the input from the thickness control program repeated for the next stand, as indicated in blocks 84 and 86. In one application of the invention, the

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Input from the thickness control program for each of the seven Roll stands S1 to S7 are carried out every 0.2 seconds, i.e. at the speed of the analog scanning of the pressure cells 34 supplied rolling force signals.

The density control program effects advance control in a tandem mill with tension control. The changes in the setting for thickness correction cause changes in the material passing through, which result in changes in the height of the rollers L provided between the rolling stands, and these height changes cause corrections in the rolling speed which lead to the restoration of perfect rolling conditions. The thickness control program includes logic for determining ψ ^v inputs to orausregelung, which are fed directly to the speed controllers so that the speed is increased to the respective rolling stand as a function of job changes.

If the program for the employment is executed in response to a call from the thickness control program, the the respective adjustment position is compared with the adjustment point of the adjustment position for each regulated rolling stand and an output signal released so that the adjustment motors with optimally or critically damped adjustment time curve in accordance with the Total amount of pitch movement can be operated. If the adjusting screws of the specified, corrected adjusting " approach position, the servomotors are slowed down with critical damping. The speed time curve and the pitch time curve for the adjustment motors, the critical damping of which depends on the different extent of the adjustment error, are determined empirically or partly empirically and partly by calculation for each roll stand.

The thickness control system has a uniform structure to improve the implementation of thickness control on rolling mills. the Control device preferably comprises a digital computer which controls the employment of one or each of several Roll stands regulates the rolling force when the plasticity or the values of the spring constant change. A ver

009 82 8/099 0 - " ^q -

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improved coordination of the control behavior on each roll stand is made by the advance regulation and by the automatic determination the plasticity achieved on every regulated roll stand from the rolling force and the adjustment. This creates a achieved faster, more precise and more stable control of the thickness and a reduced delay in control interventions. The application of the control system finally brings an improved one Uniformity of the thickness of the rolling stock and a higher productivity of the rolling mill with it.

7 claims
4 figures

- 30 -

0 ^ 9128/0990

Claims (7)

Claims 1] means for controlling the rolling-stock thickness in a rolling ^ ~~ ^ plant comprising at least - contains a roll stand with a control device for the adjustment of the roll gap, with S ¹ UH _<learning for detecting the rolling force and the setting position, of a Device for determining the rolling force error from the measured rolling force and a rolling force setpoint and from the respective actual value and a predetermined setpoint of the setting position and with a device for determining the size of the setting movement required to correct the thickness error, characterized in that the device for determining the setting movement comprises a device which determines the corrective variable for the pitch movement in accordance with a relationship between the values for the plasticity of the rolling stock and the stator elongation constant as a function of the change in the rolling force caused by a change in pitch and influences the pitch control lets 2. Device according to claim 1, characterized by multiple ■ input of the value of the plasticity determined by the device in the regulation of employment during at least part of a whale season. 3. A device according to claim 2 characterized in _t that a minimum amount of · adjusting movement is required for entering the plasticity value, 4. Device according to claim 3 »characterized in that ΈΙ £ in a multi-stand rolling mill equipped with a thickness control device equipped with such a device only determination of the plasticity of the rolling stock iat. 5. Binding according to claim A--, dp.riu.reh gekenns5eicim »t _t that the device on Erni-5'clur.g de & ValzkraXifehlers and de * An-Btellbewegung is a digitally working Hechner, whose 0098 ^ / 0890 '_ ₃₁ _ - 31 - VPA 69/8232 Inputs with the sensors and its outputs with the device are connected to regulate the employment, and that a program is provided for the computer that the from the rolling force and the pitch changes determined values of the control and the rolling force error as well the pitch movement is determined. 6. Device according to claim 5, characterized in that the device for determining the plasticity value Relation P =] is based on, in which DS / Tue ¹ - 1 / K K is the stator elongation constant, DP is the change in rolling force and DS is the measured change in the pitch position, 7. Device according to claim 6, characterized in that the plasticity P and the required for Diclcenkor correcting Adjustment movement through the program from the rolling force error and a size ?? + ^ is determinable. 00982 8/0990 L ee rs ei \ e