DE1527671A1 - PROCESS FOR STRIP THICKNESS CONTROL IN COLD ROLLING MILLS - Google Patents

Description

LICEIiTIA ΡΔΤΕΝΪ-VERWALajüNöS-G ^ M.B.H. 6 5 * Rankfurt / Main, Theodor-Stern-Kai 1

Wegener / scho j Weg 31/01?

Process for strip thickness control in cold rolling mills

The invention relates to a method for strip thickness control in cold rolling mills in which the thickness deviation is recorded by a thickness measuring device located behind the roll stand and after reshaping in a downstream function generator for Issue of an adjustment command for changing the roll adjustment or the strip tension of one as a function of the rolling speed controlled clock system is switched on »which is designed in such a way» that further setting commands only then are given when the effect of the first setting step is detected.

With thickness regulations of this type, the strip thickness is exclusive influenced in the roll gap. However, since a thickness measuring device cannot be arranged here, the control loop is based on the so-called Traneport time afflicted. This is the time when one

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The strip point from the roll gap to the thickness measuring device runs. The because of This voting time necessary stabilizers have a slow and sluggish control results in »One therefore already has Scanning controls are used in which, after an actuating command, there is a wait until the transport βIt has passed before a a new heating process is initiated and, if necessary, adjusted Deviation is regulated to zero or at least within narrow specified limits as far as possible due to the effect of an actuating command Difficulties arise here because the parameters of the controlled system are variable «, depending on the work hardening, Bandwidth and steel quality result in a different deformation resistance of the rolling stock and thus different expansions of the roll stand * the different sized adjustment steps to move the roll adjustment or to change the belt tension with the same thickness deviations require

So far one has helped that for the transfer behavior a mean value has been permanently adjusted for the control system. At best, this value was corrected by hand based on empirical values and observations.

The invention is now based on the object of creating a method for strip thickness control in cold rolling mills and specifying a control device for carrying out the method, * ^% which make it possible to automatically adapt the adjustment steps of the thickness control to the deformation resistance of the rolled stock.

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This task is solved according to the invention by the fact that the transmission behavior the regulation through an adaptive feedback to the existing deformation resistance of the rolling stock is adapted automatically ο

The method according to the invention results in the following in particular compared to the previously used thickness regulations essential distributions:

Once the operator is aware of the task that is made up the ongoing Heue inst position of the control device results, relieved and on the other hand is above all a setting gained that the operator cannot reach because either the operating conditions change too quickly or manual adjustment cannot be carried out precisely enough. In addition, thickness errors and thus a reduction in the proportion of the non-dimensionally accurate tape is achieved »

According to one embodiment of the method according to the invention, the automatic adaptation of the transmission behavior of the control to the existing deformation resistance of the Rolled stock can be achieved, for example, by applying a voltage corresponding to the deformed control deviation charged capacitor is discharged to issue the control command via a resistor whose Entladezeitkonetaate in Dependency on the size and sign of the from the Diokenmeßger & t supplied control deviation remaining after one setting step

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will be changed.

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To carry out the method, a control device is proposed according to a further feature of the invention, in which means are provided which the further switching of the control deviation remaining after a setting step to a Veratellsyatem for the Eatladezeitkonatant © only at the clock following the setting command dea controlled by the rolling speed All suitable gowns can be used with particular advantage, for example, contactless switching electronic control elements in such a way that the adjustment system for the discharge time is preceded by a gate, which is controlled by the output signal of an AND element, the first input of which is from the am The output of the clock system controlled by the rolling speed and its second input are acted upon by the signal that occurs at the output of a bistable multivibrator when a control command is given. :

Further details and advantages emerge from the following description of an exemplary embodiment. To illustrate such an example, the schematic diagram of a strip thickness control according to the invention is shown in the drawing.

The thickness deviation /. +

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It is a proportional element, but instead travels with acceleration and deceleration in triangular operation due to an actuating command. In the the function generator 1 converted control deviation is from a

Clock system 2 to be determined Tent points switched to the world · In

the rest of the time the control loop is interrupted. This ensures that the control loop is interrupted during an actuating time and the subsequent transport of the belt from the actuating location to the Keßort, so that it is first waited until the effect of an actuating command has been measured. Only then is a new control process initiated. The clock system 2 receives the Valsgeechwindlgkeit Vy _alfi as a working variable, for example from a tachometer machine that is coupled to the rolling motor. When the clock system 2 closes the control loop, a capacitor 4 of a capacitor system 5 is charged with a very short charging tent with the control deviation transformed by the function generator 1 the employment receives the command

The ratio of control deviation A h and discharge side of the capacitor determines the transfer behavior of the control and thus the setting steps. At very high Verfoxmungswiderstand of VaIsguteβ the Sntladezeitkonstante must be very high, can be very small with very soft material · The automatic adaptation ^p of Entladezeitkonatante to the respectively existing resistance to deformation is effected by means of an adaptive (self-adjusting) recycling · Here, one goht thereof AU3 that dio

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Belt thickness changes only slowly. In the chosen exemplary embodiment, the adaptive feedback is a bistable one. Trigger stage 6, an AND element 7, a delay element 8, a Gate step 9 and an adjustment syst em 10 formed.

After a control command of the thickness control must be correct Setting of the discharge time constant the thickness deviation is within the specified tolerance limits If this is not the case, so the discharge constant must be corrected · Hit Help the bistable flip-flop 6 it is determined whether a control command has just been issued. With the next impulse of the clock system 2, both conditions appear at the output of the control command that has just been given and the following control command Clock of the clock system) summing AND gate 7 a signal By controlling the gate stage 9, this output signal causes the control deviation supplied by the thickness measuring device to be passed on to the adjustment system 10 for the discharge time constant the thickness deviation caused by the insensitivity area 11 exceeds specified tolerance limits. The change in The discharge time constant can, for example, take place by adjusting the resistor 5 by means of a stuttering motor or by means of a relay or switching transistors, eiβ individual stages of the resistance switch on or off. The delay element 8 ensures that the flip-flop 6 is switched back again after this process has run.

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6 pages description

5 claims

1 sheet of drawings οηαο ^ ο / η / β *

Claims (1)

t LICENTIA PAOJEMT-VERWAI / HJHGS-G.M.B.H. 6 FrankJFurt / Main, Theodor ~ Stern-Kai 1 Wegener / echo Weg 31/017 patent claims t 1. Method for strip thickness control in cold rolling mills, at which the thickness deviation is detected by a thickness measuring device arranged behind the roll stand and after forming into a downstream function generator for issuing a control command for changing the roll adjustment or the The strip tension is switched on in front of a clock system which is controlled as a function of the rolling speed and which is designed in such a way that further setting commands only are given when the effect of the first setting step is detected, characterized in that the transmission behavior of the control is automatically adapted to the respective existing deformation resistance of the rolling stock by adaptive feedback. 2 »Method according to claim 1, characterized in that a with one corresponding to the transformed Hegel deviation Path 31/017 Voltage charged capacitor (4) for issuing dos control command is discharged via a resistor (5) whose Discharge time constant depending on the size and sign of the one supplied by the thickness measuring device after a setting step remaining Hegel deviation is changed * 3 · Hegel device for carrying out the method according to claims 1 and 2, characterized in that means are provided which forward the control deviation remaining after an adjustment step to an adjustment system (10) for the discharge time constant only with the cycle of the cycle system controlled by the Valzgesohwlndigkelt (, 2) following the control command * 4-. Control device according to claim 3 »characterized in that that the adjustment system (10) is preceded by a gate stage (9) which is controlled by the output signal of an AND element (7) whose first input is controlled by the signal occurring at the output of the clock system controlled by the whale speed and whose second input is controlled by the signal at the output a bistable multivibrator (6) are acted upon by a signal occurring when a control command occurs «. 5 »Hegel device according to claim 4, characterized in that that the bistable multivibrator (6) from the output signal of the AND element (7) after a delay that can be set on a timing element (8) has elapsed from the memory position into the hole position is tilted back. 30983 3/0486