DE1913105C3 - Control device for a four-roll stand with two work rolls and two backup rolls - Google Patents

Description

The present invention relates to a control device for one two work rolls and two Four-roll stand with back-up rolls, with pressure sensors for measuring the amount on the rolling stock transferred rolling pressure between the back-up rolls and the stand and a control loop for to the Hydraulic bending cylinders attacking the roll necks of the work rolls, through which the surface curvature of the work rolls in the axial direction substantially proportional to that on the workpiece transmitted rolling pressure can be influenced, this control loop inputs for the determined rolling pressure signal and for a bending force signal derived from the hydraulic bending cylinders and a corresponding one The output signal that is dependent on the ratio of the rolling pressure signal and the bending force signal is generated, its comparison with a preset ratio value a signal for the application of the rolling force setting device supplies, wherein the control circuit is provided with an adjusting element with which the relevant ratio value can be set as a function of a rolling stock parameter.

A known control device of this type (US-PS 33 18 124) consists of a circuit which over one line a signal corresponding to the rolling pressure applied to the rolling stock, and one line Winding received signal that corresponds to the bending force applied to the bending cylinder. the The circuit then outputs an output signal to a control unit when related to a preset one Relative value of the rolling pressure and the bending force signals is a difference. The preset ratio is set with the help of a potentiometer, which is controlled by a motor is.

In the known device, the rolling pressure signal is applied to said circuit before it is supplied changes. This change is achieved by supplying the actual rolling pressure signal to the transducers reaches the circle, which emits an output signal via a line that is the difference between your actual rolling pressure signal and a preset differential rolling pressure stress. The purpose of this Arrangement is the difference between the

with neuter roller pressure and the preset Keep value proportional to the bending force.

In the case of the known control device, the pre-set rolling force must either be in advance. a WaIzkreftspeicher automatically _o the kit are derived during operation of the Walzwer- so that the desired difference signal may be derived, further followed by a circuit adjusts a potentiometer. Subsequently, the setting of this ratio requires setting the operation of the rolling mill until an operator has determined that the desired shape of the rolling stock has been achieved. After setting a hydraulic valve for setting the cross-section of the rolling stock, the operator closes a switch so that a motor controls the ratio setting to the desired size. Then, the automatic control for the bending force is carried out by comparison within the former circuit between the differential rolling pressure signal and the actual bending force signal.

In known control devices, the ratio setting is thus made as a function of the desired one Shape of the rolled stock. For this, however, it is necessary to put the rolling mill into operation until the desired shape is achieved. In this case, however, not only the width of the rolling stock, but also some other factors must be taken into account.

The object of the present invention is to provide such a control device of the type mentioned at the beginning to develop that the rolling process quickly and easily without an upstream trial rolling process can be initiated using as few settings as possible.

This aim is achieved according to the invention in that the control loop has an electrical loop, in which the established rolling pressure signal and the bending force signal compared to one via a third Input supplied deformation control signal can be brought to compensate and by means of the setting element the relationship between the actually determined rolling pressure signal and the bending force signal in Depending on the width of the rolling stock to be rolled can be set in advance.

According to the present invention is a ratio adjuster intended. This is effective to determine the relationship between the actual rolling pressure signal and the bending force signal - but not the relationship between the To form the differential load signal and the bending force signal. According to the invention, this ratio of set in advance, whereupon there is no subsequent adjustment by an automatic control device more needs to be done. According to the invention, the ratio setting is carried out accordingly the width of the rolled material.

The advantage of the present invention lies in the possibility of initiating the rolling process very quickly and easily with the aid of two settings that do not require any particular skill. The ratio setting is carried out by hand according to the width of the rolling stock. In order to carry out the ratio setting, it is therefore not necessary to carry out a test rolling process in order - as is the case with known devices - to determine a desired cross-sectional shape. As is known, test rolling operations are not only time-consuming and expensive, but also difficult to carry out because the determination of a desired cross-sectional shape of the

Rolled stock requires a very high level of skill.

The only other setting within the scope of the present invention is the setting of the bias voltage of the control circuit with the aid of the setting element. Under normal conditions, this setting does not require a test run either.

Advantageous further developments of the Erlindung emerge from the patent claims 2 to eighth

In the following the invention is explained and described on the basis of exemplary embodiments, reference being made to the drawings. It shows

1 shows a simplified diagrammatic view of a rolling mill with a control device according to the invention,

2 shows a side view of an inventive Rolling mill including circuit diagrams of the regulation and control device,

3 shows a diagram of the hydraulic system according to FIG. 2,

F i g. 4 a circuit diagram of a rolling mill according to the invention,

F i g. 5 is a schematic view of the shape control with the associated circuit diagram.

The four-high roll stand 10 shown in Figure 2 has upper and lower backup rolls 12 and 14, respectively Trunnions are carried in bearings 13 and 15, respectively, and those with upper and lower work rolls 16 and 18 in Are connected, which in turn are supported by bearings 17 and 19 by means of trunnions. This structure is carried by a stand 20 which acts on the bearings 13 of the upper pressure roller Has adjusting device 22 with an adjusting drive 23.

Fig. 1 shows a diagram of the roll stand, wherein the housing and the bearings as well as construction units of the roll stand omitted for the sake of simplicity, or as the drive device 25 for the rollers, have only been shown schematically.

Compensating cylinders 28 are arranged between the upper and lower bearings 17 and 19, respectively. Between The bearings for the work rolls and the upper and lower bearings for the backup rolls are in turn bending cylinders 30, 31 arranged, the bending cylinder 30 between the upper work roll and the upper Back-up roll and the bending cylinder 31 between the lower work roll and the lower back-up roll is located. All of these bending cylinders have solid hydraulic cylinders with sturdy pistons that do so are designed that they exert a force on the dependent roller bearings. Between each pair of rollers two cylinders can be arranged on each side of the roll stand as shown in FIG. In another Embodiment of the invention, the roll stand has a cylinder on each side. In another Embodiment of the invention can have more than two cylinders connected in parallel on each side of the Roll stand be attached. Fi g. 1 shows on each side and on each point only for the sake of simplicity a single cylinder. In all cases, the hydraulic cylinders are connected in parallel, such as this, for. B. from Fig. 2 can be seen. There are all four above Cylinder 30 (including the opposing pair, not shown) simultaneously by means of a individual feed line fed with a pressurized hydraulic fluid. The same applies also for the cylinder 28 and the cylinder 31.

This complete system of bending and balancing cylinders provides a device for exercising one

Pressure on the bearing journals of the work rolls relative represents the entire stand in engagement with the adjusting device, the direction and the extent of these forces on the relative values of the original pressure and the resulting Displacements of the cylinder piston depends. Therefore, when the bending cylinder pressure is dominant, will the ends of the work rolls are bent towards each other ir elimination of the "thermal crown" (crowned value of Rolling due to thermal influences) of the rollers or to achieve a curved roller gap. If the pressure exerted by the compensating cylinders is greater than that of the bending cylinders, the ends of the work rolls are bent away from each other. Those exerted on the work rolls Bending forces, whether they are due to the workload or exercised by the hydraulic system, each move within the elastic limit Working roller c. The bending force can be measured from the overpressure in the dominant cylinders.

The entire structure is under a workload, that is, by means of the adjusting device on the bearings of the back-up rolls and on the other rolls of the whale / stand. the stand foot 36 of the rolling stand exerted pressure for the desired reduction of a strip 35 made of aluminum or another metal guided through the roll gap 16, 18. The rolling band is fed from the reel 38 having a shaft 39, the reel being provided with a device, not shown, for maintaining a braking tension on the band section 35.1. The section 35; i is guided through the nip of the working rolls and comes out on the other side of the same in the desired thickness and is wound on a reel 401 which has a shaft 411 and is driven by a drive device 411; /.

In the one in I 'i g. In the roll stand 10 shown in the figure, the hydraulic connection leading to the upper and lower levels 30, 31 consists of the lines 40, 41, which open into a common line 42, while a similar hydraulic connection / u the compensation / yliiulcm 28 viewed by means of a line 44. The hydraulic oil is supplied and transported to the equalizing and lifting cylinders by means of control valves which have a hydroelectric control valve 50 having an electrical safety winding 52. where the SU'ucrspulc is shown in dashed lines for the circuit diagram both in the valve and in the dingrnmmntisch. Hydraulic fluid is conducted at high pressure through the line 54 / around the valve and requested via the line 5h / back / u a suitable tune.

The (roundness of the whale crust is proportio monthly with the / wipe the StUlzwal / .en and the Wul / gerüsisiündcr measured workload practiced or on (5round of protrusions in the Workload that is ongoing means of a couple / wipe the Siüt / wul / s and the whale / .gcrllstsittndcr attached Mcßzellcn 60 is measured. Magnetic cells, Hydromctei or a voltmeter can be used. To the Αημ.ιΙη the (iesumihelustung are the MetJ / ellcn 60 with Siimmieriingsgcrtttcn not shown connected to each other.

The Mcß / Elli-n 60 speak a terminal 62 Mi. so ditlJ and the connections 61.64 of the same generate an electrical socket! whose strength varies in proportion to the total workload measured.

The valve 50 is adjusted by means of a control winding 52 which is controlled by means of the measured signal of the workload from the connections 63, 64. The control unit 52 has a simple control circuit 65 connected in series which, in the event of an asymmetrical load, transmits a signal to the connection 66, 67 of the coil, if necessary via a suitable amplifier 68 or a similar device, e.g. B. to feed the coil in accordance with a voltage signal in control circuit 65.

The connections 63, 64 are at the input of an adjusting element 70, for example a potentiometer linked together so that the signal of the measured workload is a variable, reduced Output signal of the workload to the terminals 71, 72 emits, for the sake of Simplicity are shown as part of the control loop 65.

An independent bias signal is also applied in the same series-connected circuit the connections of a third input 73 and 74 delivered, the connections being the output of a Form Vcrformungsstcuerkrcises 75, which in Fig. 1 with

ij of a high voltage source 76 at the input of the potentiometer 77 is shown. To read off the pressure in the compensating or bending cylinders, subtraction circles 80, 81 are provided, which are connected via lines 82, 83 to lines 40, 41, 42 of the bending cylinders and to line 44 of the compensating cylinders. For the sake of simplicity, all elements transmitting a signal are shown in FIG. 1 as direct current elements.

The outputs of the Sublraktionskrcise are in series, but switched against their polarity and generate the connections 86, 87 a signal which corresponds to the pressure difference of the compensation and The bending cylinder varies and therefore the total measured value exerted on the bearing journals of the work rolls Represents bending force. The connections 86, 87 form part of the control circuit 65 and are used to introduce the KuckkoppUmgssignuls in a general opposite Relation to the control signals sent to clou Connections 71, 72 and 73, 74 of the third input

4) are handed in. The output voltage of the workload is a varying current voltage at positive polarity at terminal 72 which is connected to the left terminal 66 of the safety winding 52.
The mold bias signal is a direct current

SQ voltage with one of the signal of the workload opposite poluritute, d. H. the terminal 73 on the side of the opposite terminal 67 of the Safety winding 52 has a positive oluritttt. at an output of the subtraction circuit 80, 81 connected in opposite directions and connected in series htlngi the polurity and the value of the ncttosignuls un the outputs 86, 87 from the pressure differences measured by the transducers. Went ζ. B. the pressure acting on the bending cylinder

If the largest word is 0, the feedback signal is applied to the one close to the connection 67 of the feedback 5; Terminal 87 has a positive polarity, but when the pressure acting on the compensating cylinder has the highest value, ie when you see this

If you bend the bearing journals of the work rolls more or less towards each other, the signal will be sent to the aforementioned Terminal have a negative and at terminal 86 a positive terminal.

The function of the entire circuit leading to the control coil 52 is to create a voltage of the coil that responds to an asymmetry in the control circuit 65, the excitation taking place in the direction and strength of the asymmetry. The valve 50 is then operated in a compensating direction and extent, so that an increase in pressure in the corresponding compensating and bending cylinders and a pressure decrease in the other corresponding cylinders takes place, until a change in the reading of the subtraction circuits 80, 81 re-establishes the equilibrium in the circuit .

The system corrects itself automatically, that if there is a leakage or another defect The error signal to be returned in the compensating cylinder is emitted, the control winding 52 and the valve 50 can be operated in such a way that the original conditions are restored.

The control valve 50 has a control piston 90 which is provided with three shooting pistons 91, 92 and 93 which are arranged at a distance and which is normally in the closed position with respect to an outlet opening 95. It also has an inlet opening 96 and another outlet opening 97, the outlet openings being connected together and with the outlet line 56. Openings 98 and 100 are arranged between the openings 95, 96 and 97, which are connected to the lines 40 and 44 of the bending and compensating cylinders and are located either opposite the inlet opening% or the outlet openings 95 and 97 by means of the corresponding shooting piston 91, 92 and 93 are closed in their initial or equalization position.

The annular control winding 52 is mounted in an annular space between opposing poles 102 and 103 of a permanent magnet. The magnet is completed by a central part 104 extending to the pole 103 and the connecting sections 105 and 106, which can be permanently magnetized. The control winding of the coil 52 carries a cone 108 which extends to a centering element 110 , which in turn is pressed against the membrane 112 in the stub opening 115 by means of the spring pressure of the spring 113. The suite opening leads from a chamber 116 which is continuously fed with a pressurized liquid (through a suitable inlet opening) from an auxiliary conduit 118 to a secondary conduit which leads around a piston 92 to the inlet opening. From the outside of the opening, that below the Stut / ens, leads a passage 120 including an outlet opening to the Ausluüöff · s ° voltage 97. The Kommer 116 is by means of a narrow confining 122 mil the Rüeklcil the chamber into which the Steucrkolbcn 90 moved, the fluid pressure exerted in chamber 116 continually pushing the spool in one direction. 5 $ d. h, gcmüB the drawing on the left, this force being balanced in the normal range by a spring 124 that is disordered at the other end of the piston, the spring being designed to be adjustable by means of a screw 125 acting on its rear end. * °

If the control winding 32 does not exert any force, the piston 90 is held in the neutral position shown. Is current in one direction through the winding run, for example around the spool to move to the left, the socket is closed and hydraul! · ⁶ S see liquid is delivered ^ relieve pressure on the balance, while liquid from the equalizing cylinders with one of Ventilspulchbcwegung corresponding speed flows back. If this movement takes place in response to an error signal, a corresponding change in the net feedback signal at the connections 86 and 87 reduces the current flowing in the control coil to zero, whereupon the pressure prevailing in the chamber 116 assumes the normal value and the coil returns to its starting position, while the Compensating and bending cylinders assume a position corresponding to the change in pressure. As a result, the bending force acting on the bearing journals of the work rolls is changed accordingly, ie in this case they are bent apart.

If a current flows in the opposite direction through the control coil, the opposite effect occurs and the journals of the work rolls move towards each other. When the electrical circuit is by means of a change in the feedback signal at the terminals 86 and 87 is balanced again, the falls The current flowing in the control winding 52 drops to zero and the control piston 90 moves into the starting position back.

In considering the control circuit 65 and its function described above, it is assumed that a strip is rolled between the work rolls and by means of an initial set pressure, with the rolls rotating slowly. The setting element 70, which is calibrated in width units, is set according to the bandwidth prior to the operation, whereby the output signal of the workload at the connections 71 and 72 is set proportionally to the signal read from the measuring cells 60 , so that any change in the measured workload is precisely compensated for can. With a closer look at the emerging rolling stock or with other measurements, the potentiometer is now adjusted until the compensating cylinders achieve the desired constant thickness of the rolling stock. Adjustment is complete when the slowly moving rolled stock has the desired thickness.

When the rolling speed is very slow, the workload (initial force exerted) can be substantial and a correspondingly large workload output at terminals 70 and 72 is produced. Furthermore, it can be assumed that this high workload bends the ends of the work rolls against each other and not only overcomes the so-called "thermal crown" but also creates a concave shape and a convex design in the central area of the work roll. The potentiometer 77 is adjusted in such a way that the rolled strip has a constant! Has thickness and the pressure prevailing in the compensating cylinders is greater than that in the bending cylinders. In this case, the bias signal from the potentiometer tcr at terminals 73, 74 is equal to the algebraic sum of the output signal of the workload at 7t, 72 to the feedback signal (negative at terminal B6) from the subtraction claws 8t, 82. The form voi is voltage signal the value by which the workload output must be reduced to the same level as the feedback signal. which depends on the bending forces acting on the pressure cylinders, which are necessary for a parallel Bcorbeltun. Dcmuf retains the pretension! signal for the form at this value until the operator finds that other Würmebedlngui

708 632/8

conditions prevail, so that a readjustment of the potentiometer 77 is necessary.

The rolling mill is then reduced to normal operating speed while reducing the load brought. A reduction in the workload is determined by means of the measuring cells 60 and causes a corresponding reduction of the output signal at connections 71, 72. The resulting asymmetry in the circuit causes the above-described hydroelectric control valve 50 to be actuated, in particular in FIG direction to increase or decrease the pressure in the compensating or bending cylinders. This causes a certain change in the bending forces acting on the bearing journals of the work rolls to maintain the parallel form of what is under the changed workload Roll gap. One of the loads can be of such magnitude that there are no net bending forces are necessary and the cylinder forces are the same, the outputs 86 and 87 have a zero signal.

Figure 3 shows a detailed diagram of a suitable hydraulic system. The reservoir 130 contains a suitable hydraulic fluid, which is withdrawn by means of a pump 131 and conveyed in the high-pressure line 132 via valves including a control valve 133. The line 132 extends to the inlet 54 of the control valve 50, from which the output line 56 leads via a spring-loaded valve 134 to the main return line 135 which is connected to the reservoir. The fluid pressure prevailing in the supply lines 132, 54 is kept constant at a high value by means of a conventional accumulator 137 , which compensates for temporary pressure fluctuations, and by means of a pressure relief valve 138 leading from the line 132 to the return line 135 , the setting of which is to maintain a maximum supply pressure serves.

Line 44 extends from control valve 50 through manual normally open valve 140 and remotely controllable valve 141 to the equalizers. The valve 141 can be actuated by switching off a solenoid 142 , so that the inlet 44 '' to the compensating cylinder of the rollers is switched over and the liquid is diverted into the line 135. Likewise, the feed line 42 for the Nicpczylinclcr extends via a manually operated and normally open valve 144 to the lines 40 and 41, which lead via the remote control valve 146,147 similar to the valve to the upper and lower bicycles. When the valves 146, 147 are in a normal position, the lines 40, 41 are connected to the supply lines 40u, 41u for the flexible cylinders. A control valve 134 prevents complete emptying of the cylinders when the line 36 is connected to one of the lines 42 and 44, respectively. The fire setting of this control valve allows it to be opened only at a minimum pressure which is high enough to prevent the cylinders from collapsing when the machine is at a standstill, which nevertheless allows a desired reduction in the number of cylinders for the automatic function described Filter, e.g. B. at 448 and 449.

When the Aiitomutik is out of operation, the valves 140,144 can be closed and the normally closed valves 140 / 1,144 «can be opened, whereby a connection is established from the high pressure line 132 via various lines to the remote-controlled valves 141, 147, 146 , the latter is also manually controllable, which z. B. is important when replacing the rollers.
The magnitude and the direction with which the control valve shown in Figure 3 50 and the control piston 90 shown in Fig. 1 of the output from the winding error signal is activated with respect to the magnitude of the pressure applied to the balancing or ίο bending cylinders corresponds. If the feedback signal emitted by the subtraction circuits performs a corresponding change to compensate for the error signal, and thereby drops to zero voltage in the control circuit 65, the current in the control winding 52 drops to zero and the control piston 90 returns to its starting position, with all hydraulic lines for the cylinders are closed.

The preload valves 148, 149 are arranged in secondary lines between the compensating or bending cylinder lines 42, 44 and the hydraulic line 132 and 54 . These valves have a high preload and remain in the closed position up to a pressure which exceeds the normal supply pressure. But if in the lines 42,44 (or in one of the two) a high pressure acts, such. B. at the end of a passage, the control valve is bypassed and the pressure increase is kept below a safety level.

The roll stand 10 according to FIG. 2 contains a preload for the support rollers 12, 14 due to the arrangement of pressure cylinders 150 located between the upper bearing 13 and the lower bearing 15. These pressure cylinders 150 are by means of a device shown in FIG. 3 , the branches of which lead to the various cylinders 150 in a conventional manner, not shown, are connected to the hydraulic system. The hydraulic fluid is fed from the supply line 132 via a line 155 to the line 152 via a remotely controllable valve 154 which is designed similarly to the valve 141 . If desired, a manual or some other control can be provided for the pressure acting on the bearings of the pressure rollers. For the sake of simplicity, however, FIG. 1 shows these pressure cylinders under full hydraulic pressure which is exerted at the same time or before the adjustment of the adjustment force at the start of rolling.

Fig.2 shows an arrangement for achieving a

so net signnls of workload in electrical

Ladders 156, 157. the one further arrangement 138

have, in turn, a reading of the

Pressure cylinder 150 acting Gesiimtdruckcs (over

Lines 162) by means of a suitable voltage on

S3 enables converters 139 and 160. The control

of the measuring device 164 takes place by means of the measuring cells 6C

via appropriate electrical connections Ιββ

This arrangement creates one at the conductors 167, 168

Tension, the entire of the adjusting device

«O exercised on the support rollers and by the measuring inchers

represents measured force. The signal from dei

Arrangement 138 is from a measuring device 164 Ir

a Subtrahlerungskrels 170 emitted signals

subtracted, the measured net signal dei

Workload in the ladders »36, 137 donated

will,

Fig. 2 is a measuring device 172 for measuring the current thickness of the rolled coil 33 />"owl"

a control device 173 responsive to the measuring device for setting the adjusting device, d. H. the workload, and to maintain a uniform predetermined thickness of the material. If the Adjustment device is set to control the material thickness, corrects the control device according to the invention automatically the bending of the work rolls caused by a change in the working pressure, so that a uniform material thickness is achieved. ίο

4 shows a schematic representation of a control system according to the invention which is used in a roll stand together with a hydraulic system of pressure cylinders. The control winding 52 in FIG. 4 actuates the control or servo valve 50 in FIG. 1 and 3 and a circuit 170a formed in accordance with the subtraction circuit 170 in FIG. 2 feeds a direct current voltage which varies in accordance with the measured net workload on the conductors 156, 157.

The circuit in FIG. 4 contains electronic servo control units 175, 176 and 177 which are designed to receive an AC input signal and one or more DC signals with control bias voltage and which emit an amplified electrical current. $ 2

The subtraction circuits 80; i, 81a connected to the hydraulic lines of the compensating and bending cylinders in the same way as the subtraction circuits 80, 81 in FIGS is displayed by 180 °. The circles 80.), 81a are excited by an alternating current source 178, 179 and contain adjustable resistors 180, 181 for a preset. The interconnected output of the reconnected opposing connections of the subtraction circuits is led to the servo control unit 176 via the conductors 183, 184 (the circuit is simplified by means of the earth connections shown such as ■ / .. B. 184 ) and the input 185.

This control unit 176 contains an alternating current amplifier 186 which sends an alternating current output signal to the line 188 , the strength and direction of which depends on the signal signals coming from the pressure and compensation cylinders 4. The signal at 188 is a single-phase alternating current signal, the amplitude of which depends on the direction and magnitude of the forces acting on the compensation cylinders.

This signal is converted into a direct current signal by an amplifier rectifier 190 and fed into the line 191, which is connected to a direct current converter 192, the voltage of which represents the pressure differences between the bending and compensating cylinders. When the pressure prevailing in the bending cylinders reaches a maximum value, this signal can have a zero voltage, while at a maximum pressure in the compensating cylinders the signal has an intermediate value representing the pressure difference.

Furthermore, a continuous signal leads from the manually set poicntiometer 77a via the conductor 194 to the amplifier 192 and a further continuous signal from the potentiometer 70 'provided for side control via a conductor 193. For the sake of simplicity, the backs of these biased input signals are omitted, with the exception of the second side of bias for shape control at 1%. While the latter bias may be of a simple magnitude, it may be advantageous to have the mold bias adjusted by yourself in those cases where the bias or feedback signal from the transducers (on line 191) is an individual variable to provide the opposite polarities extending region, e.g. B. a plus or minus DC voltage. To represent this alternative mode of the signals, the other conductor 196 or 236 of the mold biasing signal is connected to the center tap 198 of a voltage divider resistor 199, which is connected to the direct current source 200 of the potentiometer 77 «-? is connected.

The basic operation of the system is the same as that described above with reference to FIG. I, that is, with a preceding workload, the input line to the DC amplifier 192 is such that a zero current is generated in the servo winding 66, ·), 67;), and that when the potentiometer 77a is set to achieve a uniform thickness of the rolling stock , the system of compensating and bending cylinders generates a feedback signal provided with the necessary counter-effect. A reduction in the rolling pressure leads to a reduction in the pressure prevailing in the compensating cylinders relative to the pressure prevailing in the bending cylinders, a zero environmental stress being achieved for every working condition of the rolling pressure. Therefore, the Neito effect of the combined feedback and form information signal has a polarity opposite to that of the workload signal emitted by the control device 70; i over the entire total range of the working pressure.

While the specific description of the reference numerals representing the measured workload based on the net employee, see F i g. 1 or 2, it has been found that more accurate and proportionally more accurate results to achieve the exact effort for the roller deviation during a long workload by subtracting the current, opposite of the printing system Forces can be obtained from the measured signal of the working pressure. This is achieved by the Addressing the current workload related to that of the backup rolls by means of contact with the Work rolling atis-practiced pressure takes place. In other In words, an advantageous control by means of the signal of the workload will be in relation to the workload achieved in the contact line between the backup rollers and the Arbcitswalzcn.

According to FIG. 4, an alternating current signal emitted by the printing cylinder 80 ', see conductor 201, is fed to an independent control unit 177, which is designed similarly to the unit 176 . There the signal of the pressure cylinder is amplified in the Wcchsclstromverstürker 202 , essentially by means of modulation of an alternating current supplied with the same frequency, whereby the alternating current signal at the conductor 204 controls the amplifier 205 . An oil current signal is then output to conductor 206 , which counteracts and reduces the measured workload signal, as is the case with conductor 136, whereupon both signals are fed to DC amplifier 208 as control bias. Consequently, the output at 210,211 of the unit 177 represents a through dus potentiometer 170 «

represents flowing current which varies with the set signal of workload, i.e. H. The signal represents a The magnitude of the workload exerted by the backup rolls on the work rolls. The proportion of the Values of the signals extracted at 206 and 156 and passed to amplifier 208 can easily be can be measured so that the net access bias signal is a certain magnitude of the above the way described represents the set workload. How the main control works for the Output amplifier 192 and excitation of control winding 52 is basically the same as above described dimension of the simulated workload.

The control device can also have a unit for automatically controlling the deformation, the z. B. interacts with the previously set manual deformation control and a compensation for changes, for example, to the so-called "thermal crown" or others that impair the roll gap Factors achieved. These deformation control units 212 are shown in detail in FIG shown and described in more detail below.

To get a visual reading of the force difference, the collapsed Compensation and bending cylinder subtraction circuit 80a, 81a output signal via conductor 214 to a other servo control unit 175, which is identical to units 176 and 177, and on such Manner is set that the output current through the conductors 215, 216 feeds a voltmeter 218 (its Graduation indicates the forces acting on the compensating cylinder).

As already explained, the system can be used at the end of a pass (at the end of the strip of tape a Loss of voltage occurs) an automatic setting to increase the pressure difference in the Compensating cylinders are made in the direction of a greater pressure in the bending cylinders, so that the last section of the rolling stock is guided and the same is prevented from knocking out. The control this operation takes place according to FIG. 2 by means of a device for blanking a voltage loss when the rolling stock 35a enters. Since a torque directed against the development in the shaft 39 of the coil 38 is maintained, a torsion sensitive device 220 is suitable as a device for Measurement of a voltage loss provided. As with conductor 222, this feeds a signal to the Tension detector 223 which, in the event of a tension loss at the entering strip 35a, has a contact 225 closes. Closing the contact 225 closes the excitation circuit 227 via a winding of a relay 228 and causes relay contacts 230 to close immediately.

The normally open, but closed under the circumstances above, relay contacts 230 in FIG. 4th serve to feed a special bias signal via conductor 232 to the control system for the Servo coil by means of the introduction of the signals fed into the DC current amplifier 208. The special one Bias value introduced by closing contacts 230 is basically one of workload or an increase in the same opposite signal and becomes a center tap of a voltage divider resistor 235, which is connected to the power source 200, via a line 234.

This special pre-tension signal causes a bending force acting on the work rolls (against each other), where the polarity of the signal is an increase in pressure in the bending cylinders and a Pressure reduction in the compensating cylinders causes. When approaching a freed end of the tape the slightly curved roll gap ensures the desired end guidance of the rolling stock and prevents it a lateral shearing or vibration of the rolling stock by means of a corresponding centering of the same.

If the end of the rolling stock leaves the roll gap, readjustment is necessary so that the Work rolls do not loosen and a response to such a pressure loss affects the compensating cylinders acting forces does not change immediately, which would result in similar effects. The main problem is that there is no sliding or grinding contact between the work rolls and the backup rolls may arise that caused a change in shape or damage to the roll surfaces.

It is for this reason that the voltage loss sensitive coil 228 includes a pair normally closed contacts 240, which after energizing the relay after a slight delay open, e.g. B. shortly before the end of the strip enters the roll gap. A suitable time delay for a Conventional four-high rolling mill takes about half a second. According to FIG. 4 are the Contacts 240 normally used to short-circuit resistor 242 in the control winding 52 circuit closed. When these contacts open, however, this resistance is included in a series circuit and causes a strong attenuation of the response signal on the servo winding as well as on its change the control signals responding valves. In particular, the resistor 242 is formed in such a way that that the saturation voltage of amplifier 192 has the capability even at maximum power only to convey a fraction of this current that would cause the valve to open.

The amplifier 192 can have an output voltage proportional to the error input signal until the amplifier reaches a saturation level. The saturation value of the voltage becomes chosen so that the current in the control winding 52 is sufficient, the coil 90 in FIG. 1 to Limit their range of motion to move in one direction or the other, the direction of movement depends on the current of the control winding. Therefore, the full opening of the takes place in the event of saturation Valve. The control winding, designed as an impedance, causes this total current to flow from one with resistor 244 connected in series to winding 52 is balanced.

When the end of the strip material leaves the roll gap, there is an immediate increase in the Compensating cylinders prevailing pressure, which can be attributed to the elastic reaction of the roll stand stand is. Therefore, there is an essentially immediate effect on the compensating cylinders 28 of the work rolls Reaction, with a momentary increase in pressure, which in any case is a temporary maintenance causes the work rolls with the backup rolls. Both this pressure increase in the equalizing cylinders, which is measured by means of the subtract tone circles 81a, as well as the loss of workload measured by the measuring cells 60 effect in the control circuit the control winding a signal so that the control valve

50 is moved into a position causing a substantial increase in pressure in the compensating cylinders will. The activity of the contacts 240 and the additional resistor 242 result in this error signal! to a minimum value, eliminating any change in the pressure prevailing in the cylinders can only take place very slowly, with a sufficiently long period of time to achieve a maximum pressure in the balancing cylinders is obtained.

Manual control can be provided through valves 141, 146 and 147 in FIG. 3 take place, maintaining the pressure equalization in the bending cylinders and a relief of the compensating cylinder for the desired contact pressure between the work rolls and the backup rolls is achieved. F i g. Figures 2 and 4 show another design feature of the automatic machines according to the invention Device for controlling a four-high rolling mill. In this one becomes a load loss detector 250 excited about the drop in workload and optionally from the Sigriallinien 156, 157 of the Workload controlled as shown at 251, with closure of contacts 252, thereby causing the relay 253 to be energized, which moves its contact arm 254 from a normal closed position with contact 255 moved so that the circuit in the latter is released during the Circuit between the arm 254 and a contact 256 is closed. From Fig. 4 it can be seen that the normally closed contact 254, 255 forms part of the control circuit of the control winding 52, and that when the arm 254 comes into engagement with the contact 256, the control winding in this case directly by means of an independent negative voltage current source 258 is energized. The polarity of the The latter current source causes the control winding to move the valve 50 to a position (in FIGS. 1 and 3 to the left), causing the hydraulic fluid under pressure to enter the compensating cylinder is promoted, while the pressure prevailing in the bending cylinders can drop to a minimum. As a result, the desired contact between the work rolls and the Maintaining backup rolls and while the roll stand is brought to a standstill can be an undesirable Rattling can be avoided.

The system may also include a manually operated toggle switch 260 that is in its off position either to a contact 262 for constant energization of the relay 253 and for maintaining it of full pressure in the equalizing cylinders by means of the bias supply 258 (as above according to FIG. 4 described) or to a contact 264 for energizing the relay 266, which at 267 the circuit of the control winding opens and at 268 closes a connection to apply a positive voltage 269 to the Imprint control winding. In the latter case, the pressure cylinder pressure exerts its full force, the z. B. when replacing the rolls or other adjustment work of the roll stand is advantageous.

The automatic deformation control unit of FIG. 4, labeled 212 in FIG. 5 can be a Have a plurality of flatness detectors 270,271 containing measuring device, which is arranged on a shaft are, d. H. form an additional free-running roller. That under pressure from the work rolls 16, 18 emerging strip material 35c moves in rolling contact over this roller, with the individual Flatness detectors 270,271 the area and thickness of the

Feel the belt material. Depending on the type the contact of the tape painting with the roller a more or less great pressure on a specific Place anything on corrugations, indentations, protrusions 5 or other of a constant thickness of the Material deviating unevenness is due to the use of a variety of detectors 270,271 (with a detector having a length of approx. 84 mm), signals are collected via suitable collector and

ίο Distribution elements 273,274 to independent signal output circuits 275 led. It should be noted that the in FIG. 5 the rolling stand shown schematically is the same Execution as in FIG. 1 and 2 may have rolling mills shown, with compensation and

5 bending cylinder systems with the dependent control systems according to FIG. 2, 3 and 4 included could be.

Each output signal emitted by the detector has a voltage which is proportional to the deviations in the strip material at the corresponding points. The range of suitable signals is, for example, ± 10V direct current, which corresponds to a difference in compressive strength of approx. 355 kp / cm ² when aluminum strips are cold rolled. At the inven-

² S to the invention control means for the thickness of the rolled material is preferably used, the area of the side edges of the rolling stock to the controller. Therefore z. B. in the region of the connections 275 a pair of movable group switches 277, 279 are arranged, each being designed for connection to three specific measuring connections. At the beginning, these group switches 277, 279 are arranged for reading the outer area of the strip material; ie in each case over three measuring elements, what for example! corresponds to an approx. 10 cm wide band in the area of the lateral boundary of the rolling stock. The signals emanating from each side of the tape are individually summed by circuits 281,283 and combined via conductors 284, 285 and resistors 286,287 and passed to a conductor 288 which is connected to the input of a summing amplifier or delay memory 290.

In an advantageous mode of operation, the significance of the signals emitted within the lateral delimitation of the strip material decreases. Thus, of each set of signals collected by circuits 281, 283, those that are dependent on the pressure sensing elements located within the side edges of the strip material are progressively attenuated. This activity takes place by means of the independent resistors 291, 292 and 293, which are arranged in the line extending from the group switch 277. Therefore z. B. the resistor 292 have twice or four times the resistance of the element 291. A similar ratio can be contained in the resistors 291a, 292a and 293a which are arranged in the signal lines of the group switch 27'E.
The amplifier 290 outputs a signal at 295, the size of which is proportional to the sum of the surface deviation at the lateral boundaries of the rolling stock. 13 the above-described for the roller deviation For example, the output line of the amplifier at B can be connected to a unit 212 also marked B in FIG

709 632 / 6B

feeds. Such a bias can be proportional to the summation with the supply for the manual mold bias via conductor 194 or, with a suitable setting, displace such bias. In all these cases, the signal supplied to amplifier 192 is provided with the appropriate polarity to cooperate with the signal of the working pressure in conductor 195 and the feedback signal from the compensating cylinders in conductor 191 in the same manner as with respect to that of the manual Device for deformation control emitted bias signal.

As is known, the constant of proportionality of the signal in conductor 295 depends relative to the area deviation near the side edges of the strip material from the same width, because greater bending forces to the Compensation of the deviations measured in the strip material required for narrow strips are. The required settings are made by means of a variable resistor 296 in conductor 297 which is a component of a feedback loop of the amplifiers 290 (e.g. the negative Feedback of known type). Therefore, for a wider band, the constant of proportionality becomes reduced to an effective low resistance by setting the resistance 2%, while for narrower volumes a larger increase and a larger proportionality constant by means of the resistance 296 is achieved with a larger resistance value.

The feedback circuit of the amplifier 290 also includes a delay memory 298 in the form of a capacitor which compensates for the time delay of the flatness detector 270 or 271 which arises in the correction dimension. Another advantage of the circuit including capacitor 298 is the fact that the output signal in conductor 295 cannot change rapidly and is therefore characterized by a slow or delayed change (when output at B in the circuit of FIG. 4) ( in contrast to the relatively fast process of the detected workload signal). Therefore, in the arrangement of the shape control device in FIG. 5 the generation of a preload at B for controlling the roll bending forces is provided, which is large enough to compensate for changes in the roll shape which can be attributed to the action of heat, wear and tear or other factors affecting the surface of the rolling stock. The control system in Fig. 5 cooperates with the fully combined system in that it creates a compensation that occurs only very slowly for such minor values that are caused by the rapid changes in the strip thickness (which arise from a change in the working pressure) due to local misstatements can occur in the automatic control devices. Experience shows that such errors are usually minor, but the cooperative effect of the additional circuit in FIG. 5 minimizes it at least over a longer period of time.

In some cases, the control device may be to obtain a slight variation in thickness near the edges to relieve stress and prevent cracking. For this purpose, a manually adjustable in can be fed from a voltage divider 299 into the amplifier 290, the base potential of which is fed to the bias line 194 via the conductor 194/1. In FIG. 4, this connection is identified by the letter A in both views.

Another design feature that may optionally be used is the amplifier 300 marked, the output line 302 with the resistor 303 to create an additional Bias signal at the input of the delay memory 290 is connected. The feeding of the Booster 300 is done by means of a proportional to that exerted by the balancing cylinders BU: force behavioral signal, connecting the input line of amplifier 304 with point C of the line 191 is established (as in Figure 4) and wherein the feedback signal of the balancing forces, which acts as a bias to amplifier 192 of the Servo control is directed, is tapped.

The amplifier 300 contains a feedback circuit having a resistor 30 (5 and a capacitor 308), with the large capacitance of the capacitor in particular achieving such a proportionality that the amplifier output in conductor 302 can only change slowly. which is significantly greater than the changes in the roller shape due to heat dissipation, namely the signal changes occurring in the conductor 295 which are due to the:> scanning result of the flatness detectors 270, 271. Therefore, an additional supply of the amplifier 290 from the circuit including the In such circumstances, the fundamental control of the strip shape can be prevented or influenced by means of a cooling medium sprayed onto the work rolls, with this variable control tion by such spray devices over the entire length of the roll is an effective but slow mode of conventional type of roll adjustment. Together with the additional signal of the compensation or pressure forces from the amplifier 300, the manual or automatic adjustment of the atomizers over a long period of time can cause the rollers to assume and maintain such a shape that together with the original roller shape and the automatic variation of the roller changes and with the additional shape adjustment attributable to the signal in lines 248, 285, the roll stand will achieve a continuous maximum parallel surface and thickness of the rolling stock. Under these circumstances, there is a maximum range and accuracy of the rapid modulation which, by means of the forces acting on the pressure cylinders, compensates for any rapid changes in the workload, the changes being measured by measuring cells and transmitted via the conductors 156, 157 in FIG. 4 be escorted. At the end of each pass, before the rolling stock emerges from the rolls and the meter is disabled, it may be advantageous to hold the signal at I , ie at output 295 of amplifier 290, and keep it constant until the start of the next work cycle keep. For this purpose, a normally energized relay 310 is switched off for opening an internal circuit comprising two amplifiers 290 and 300 at contacts 312 and 314, respectively. The relay 310 is controlled by means of a main control circuit, not shown, for the automatic thicknesses

firing and can therefore respond to a pressure drop in the braking force of the rolling stock or to another suitable signal. For the sake of simplicity, this control, which of course can also take place, is shown as a switching contact 315 which is designed so that it performs the above-mentioned switching off of the contact in relay 310 when it is moved into the off position. The capacitors 298 and 308 can be designed as delay memories and maintain the level of the output signals in their last set values until the connection of the input signal is re-established at the beginning of the next operating cycle.

In certain circumstances it may be desirable to set the shape control to manual mode. For this purpose, a changeover switch 318 is arranged for the simultaneous control of the input circuits of the amplifiers 290 and 300, which have a first position by closing the contacts 320, 322 in the corresponding circuits to maintain an automatic mode of operation, and a second open position at 324,326, in which both Circuits are disabled, allowing manual control. Therefore, if it is desired to change the control mode while operating at high speed, changing the switch 318 to position 324, 326 will not interfere with the roll bending forces and the signal in conductor 295 will hold its value for a long time (capacitor 298 remains during operation) and also the signal in conductor 302. If the signal or the control system is to be set or adjusted again at the end of a pass, the switch 318 can be moved to a third position 328, 320 for the corresponding amplifiers 290, 300, so that capacitors 298, 308 rapidly discharge through resistors 332, 334.

Another automatic control process contained in the system (in FIG. 5) relates to the relative adjustment of both sides of the adjusting device of the roll stand, in particular to the control of the effective adjustment of the two spindles acting on the two bearings on the opposite sides of the roll stand to maintain a symmetrical constant thickness over the entire length of the rolling stock. For this purpose, the summed signal of the measuring device is fed from one side via the changeover switch 277 and by means of a conductor 340 to the amplifier 342 , while the signal from the measuring device is fed from the other side of the strip material (changeover switch 279) over a conductor 344 to the converter 346, ie an electronic circuit of known construction designed to reverse the polarity of the output, which can also be established by connecting conductor 348 to amplifier 342 . In amplifier 342 these signals are algebraically summed to produce an output on conductor 350 , this output being proportional to the arithmetic difference of the input signal.

Therefore, a signal indicating a discrepancy in the material thickness is conveyed in the line 350 to excite a relay 352 in one of two directions, this having a particularly beneficial effect when the signal exceeds a certain limit value and therefore a substantial deviation from the symmetrical constant thickness of the rolling stock in the area of the side edges. At a

Excitation of a polarized relay in one direction closes the circuit at a contact 354, while with excitation in the other direction at a contact 356 the circuit is closed

extends to the control unit 358 , which can be designed in a known construction both for differential setting of the spindles and for other purposes to maintain an effective compensation of the adjusting forces acting on the bearing blocks.

To simplify the illustration, the control device 358 is shown as it extends to the right-hand and left-hand drive 360, 362 for the corresponding adjusting elements 364, 366 of the roll stand.
While the signals controlled by the closure of one or the other relay 352 may come from other sources, a unique design feature is the use of a workload signal originating from point D in the circuit in FIG. 4 is added and via the conductor 368 in FIG. 5 is routed to the movable contact 370 of the relay 352. When the contacts 370, 354 are closed, the adjusting device is driven differentially in one direction, ie the left-hand drive downwards and the right-hand drive downwards, while when the contacts 370, 356 are closed, a differential adjustment takes place in the opposite direction, so that the right-hand drive upwards and the Left drive is moved down. In both cases, the adjustment is terminated when the difference in the signals in the conductor 340, 348 indicating an unequal thickness of the rolling stock falls to zero or below a set limit range, which brings about a new or re-establishment of symmetrical conditions in the rolled strip material 35c.

Using the workload signal at point B in FIGS. 4 and 5 to actuate the control units 358 causes the spindles to move at a speed which is proportional to the set workload signals emitted by the measuring cells. The transfer of movement of the adjusting device, which takes place in accordance with the measurement correction per unit of movement of the spindles, is carried out with reference to the net workload and to the width of the rolling stock. Hence there is a compensation

such. Variants of the transfer process mentioned are advantageous, so extreme stability conditions or an insufficiently slow response of the differential adjusting device is avoided. because the signal coming from the potentiometer 70a (on point D Fig. 4) has an exact inherent proportionality in with respect to the workload and the width of the rolling stock, causes a change in this Signal the desired compensation in a suitable way. That is, the special employment control stops automatically by actuating a polarized relay in the event of significant deviations from the normal symmetrical condition the constant de thickness of the rolling stock upright. If by means of de: Roll gap achieved thickness of the rolling stock symmetrically isi the relay 352 remains deactivated and there are none Changes to settings by means of the control units 35: required.

As described above, the change is the constant of proportionality of the measured work; load in relation to the bending force is a rectilinear function that is linear in a curve from a high Value for narrow bands runs to a low value fi wide bands (an approximation to zero takes place

for the total width of the work rolls). So z. B. the setting of the bias of a rest signal of the amplifier 208 in Figure 4 by means of a simple Testing on the running roll stand using rolled strips of different widths to achieve this of corresponding linear curves of the constant of proportionality in relation to an adjustment of the width of the belt controlling potentiometer 70a. A similar basic setting is simplified by means of a System according to FIG. 1, which is after the output of the setting element 70 in the form of a Potentiometer aligns, achieves.

An important feature of the present control of roll deviation is the independent adjustment of two components that provide the required signal or the required value of the bending forces to maintain it represent a constant thickness of the rolling stock. Therefore z. B. the according to F i g. 1 desired controlled bending force represented by the feedback signal at 86, 87 equal to the algebraic one The sum of the mold prestress, which represents one parameter, can be considered and a second bias voltage conducted by the measured workload equal to the product of the signal of the measured workload (at 63, 64) and a second parameter, this second The parameter is the constant of proportionality, which is set by means of the potentiometer 70 for width control will. Not only the second parameter represents an essential linear function of the tape strip explained above as well as all other settings of the parameters, both the last-mentioned product (the Signal at 71, 72) as well as the algebraic sum of the bias values (i.e., the sum of such Product and the mold prestress, which are adjusted to the required bending forces) are essentially are linear functions of workload.

On the basis of these relationships and their use in accordance with the method and system according to the invention, there is an effective control of the thickness of the rolling stock with regard to the changes in the working pressure and the shape of the working rolls influenced by the thermal conditions, as well as their original ground shape. In addition, it can be seen that the control of various circuits will affect a given circuit as a whole, and that accurate operation is readily achieved by simple tests such as testing the circuit diagram. B. in a first measurement of the total electrical signal (for the control of the bending forces) to achieve the real tape thickness (as it can e.g. be observed with reduced tension) for a variety of work load values (determined at points 63, 64) a given bandwidth. Since these total values can be recorded as straight-line functions, the real value for setting the pre-tension control (as a constant expression of the phenomenon) can be determined by extrapolation and then the value of the width control setting (at 70), which is used to maintain the independent straight-line function of the output (71.72 ) is required. The other variable can be determined from the value of the workload, if necessary by setting the proportionality in the reading of the measuring cells (or of the amplifier 208 in FIG. 4). A final setting of the potentiometer 70 in units of width can be determined (with regard to its own linear function) after a similar setting of this device by means of tests carried out on the roll stand (with a strip having a different width).
Thanks to these principles, including the basic linear relations, the system can be used in practically any rolling mill with optimal results, whereby when rolling a given strip the operator first adjusts the adjustment element 70 (or 70aJ to the width of the strip

ίο and then at the beginning of the rolling process at slow speed the form control 77 (or 77a) adjusts to achieve the desired constant thickness of the strip material. The bending cylinder system is automatically switched on during further operation, with the changes in the bending force necessary to compensate for changes in the workload to maintain a constant thickness of the rolled material being made automatically.

Extensive tests have shown that that

ζ »Response of the bending cylinder to a change in the Workload can be done very quickly, with a response time of less than 10 milliseconds required will. This quick response causes a more or less constant, in both directions about the Position of the zero error signal pendulum movement, which leads to an increase in the control speed should lead, but on the other hand does not have any extreme intrinsic deviations that lead to a Deterioration of a constant thickness of the rolling stock could lead. As an example, consider a Unevenly thick aluminum strip produced by the cold rolling process mentions that without the present System and with traditional working methods by hand control is made, and the corrugations or has other unevenness deviating from a parallel thickness, these deviations an order of magnitude of 10 to 100 millionths for a strip of average length in the rolled material have, while it is possible according to the invention

to reduce such errors significantly, whereby the constant thickness of the rolling stock is achieved.

As mentioned earlier, there is a linear relationship between the procedure and the control system to each other and are applicable to roll stands

which the length of the contact line between each work roller and its pressure roller is 4.5 times Does not exceed the diameter of the work roller. So were z. B. Optimal results with a quarto roller achieved with the aluminum strip in cold rolling

so go down to approx. S mm and down to approx. 0.25 mm were rolled, the diameter of each working roller being approx. 53 cm and that of the supporting rollers approx. 137 cm and where the effective length of the working pad, i.e. H. its contact line with the pressure

SS roller was approx. 190 cm. Although the dot Invention given examples refer to the Kaltwalzver drive for aluminum, the process' wise and the arrangement can also be applied to rolling in front of other metals, e.g. steel

Brass, copper and others. The procedure and dl « Arrangements can also be effectively applied to the hot rolling process. The most advantageousi Application of the present invention to existing needs is in cold rolling

⁶ S of strip metals, namely of semi-finished and finished products.

It should be mentioned, for example, that the transmission! function of the control device of the rolling stand Ii

f 1 ? ar *

* I

be / ug on the drawings with the value / • = 4.194 (1- * -)

is determined, where the factor i "represents the change in the bending pressure in kp / mm per kp of the net change in work load and w represents the width of the strip (rolled stock) in mm.

In addition 5 sheets of drawings

Claims (7)

Patent claims: 1 control device for a four-roll stand with two work rolls and two back-up rolls, with pressure sensors to measure the rolling pressure transmitted to the rolling stock between the back-up rolls and the stand and a control circuit for hydraulic bending cylinders that act on the roll necks of the work rolls, through which the surface curvature of the work rolls in Axial direction can be influenced essentially proportionally to the rolling pressure transmitted on the workpiece, this control loop has inputs for the established rolling pressure signal and for a bending force signal derived from the hydraulic bending cylinders and generates an output signal that is dependent on the ratio of the rolling pressure signal and the bending force signal and compares it with a preset Ratio value supplies a signal for the application of the rolling force adjustment device, the control circuit being provided with an adjustment element with which the relevant ratio value is dependent on A rolling stock parameter can be adjusted, characterized in that the control circuit (65) has an electrical loop in which the determined rolling pressure signal and the bending force signal can be compensated for by means of the setting element with respect to a deformation control signal fed via a third input (73, 74) (70) the ratio between the actually determined rolling pressure signal and the bending force signal can be set in advance as a function of the width of the rolling stock (35) to be rolled. 2. Control device according to claim 1, characterized in that the third outlet (73, 74) supplied deformation control signal is derived from a deformation control circuit (75). which is provided with a high voltage source (76) and a potentiometer (77). 3. Control device according to claim 2, characterized in that the deformation control circuit (75) additionally has an automatically operating deformation control unit (212) which is controlled as a function of signals from flatness detectors (270, 271). 4. Control device according to claim 3, characterized in that the automatic deformation control unit (212) has delay memories (290, 298) which reduce the response speed of the system to the flatness detector signals in relation to the detected rolling pressure signals. 5. Control device for a four-roll stand with which compensating cylinder between the two Back-up rolls and bending cylinders arranged between the work rolls and the back-up rolls are, according to one of the preceding claims, characterized in that a subtraction circuit (80, 81) is provided, which the control loop (65) one of the difference between the signals of the Compensating cylinder (28) and the bending cylinder (30, 31) supplies the corresponding bending signal. 6. Control device according to one of the preceding claims, characterized in that the control circuit (65) has a relay (253) which responds to a load loss detector (250) and which controls the compensating cylinder (2 «) via a valve (50), consequently the work rolls (16, 18) are kept in contact with the Slütz rolls (12, 14) when they leave the rolling stock (35), 7. Control device according to one of the preceding claims, characterized in that the control circuit (65) additionally has a relay (228) which responds to a voltage detector (223) and which controls the bending cylinders (30,31), consequently during the run-out of the rolling stock ( 35) the same is held in the middle between the work rolls (1 (5, 18) . B. Control device according to one of the preceding claims, characterized in that the bending cylinders (30, 31) are assigned further control units (358, 360, 362) which respond to output signals from the flatness detectors (270, 271 ) respond, whereby the flatness symmetry of the rolling stock (35) can be maintained.