DE2111608A1 - Control device for a hydraulic rolling mill - Google Patents

Description

PATENT LAWYERS Dr. rer. nat DiETLR LOUiS Dipl -Fhys. CLAUS rCHLAU

ptpUno.Franz Lohrenrz 11,744 30 / ei

8500 "NURNBERQ
KESSLERPLATZ 1

Ishikawajima-Harima Jukogyo Kabushdki Kaisha, Tokyo / Japan

Control device for a hydraulic rolling mill

The invention relates to a control device for adjusting the gap width in hydraulic rolling mills, whose lower roller system is vertically movable in relation to the upper, fixed roller system.

So far only a few manufacturers in some countries have started studying and developing hydraulic Rolling mills. Two schemes can be seen as representative for rolling:

209838/0461

ORIGINAL INSPECTED

21116 - ζ -

I. A procedure in which a more rapid response to a reduction or in view of a reduction itself characterized in that the usual, motor-driven reducing device by a hydraulic Reducing device is replaced with a hydraulic cylinder and a hydraulic motor, and in which the measure of the Reduction, i.e. generally the reduction in thickness, by controlling the amount flowing to the hydraulic cylinder The amount of oil can be adjusted by means of the hydraulic motor.

II. A method in which a prestressing hydraulic rolling mill is used, which is between the support rollers has a screw to which a load (screw load S) is communicated, which is the roll load (R) before the start of work or entry of the workpiece is equivalent, the screw load (S) with regard to the hydraulic, upwardly directed force (P) can be determined in such a way preferably in a computer it must be that the control of the gap width takes place immediately after the start of rolling. More precisely this is Moves a servo valve to control the stroke of the hydraulic cylinder in dependence on the result the calculation of

i AP / AS = (1 + m) / m i

used. 2098 3 8/04 61 *

The sizes S (screw load), P (hydraulic , upward pressure force) and R (rolling pressure) «are connected by the following equation:

P = R + S.

The values S and P are determined by means of pressure measuring cells, e.g. pressure cells. To a working according to this procedure Rolling mill refers to Fig.1, in which a pressure measuring cell a for measuring the upward Force, a measuring cell b for measuring the load on the screw, an upward-acting cylinder d and screws f are shown.

(Please note: if m is equated with Κ'ρ, the rigidity or strength of the rolling mill becomes infinite * K '^ means the spring constant of the rolling system, K ^f ₂ the spring constant of the screw system.)

In the case of the method according to I, if one compares it with the usual methods, only the difference can be found that in the case of the reduction device only passed from a system driven by means of a motor to a hydraulic system will. However, this method also has two disadvantages.

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This is because it speaks relatively slowly compared to the method that works with a servo valve at. It is also susceptible to oil loss from the cylinder itself and the connecting lines.

With the method according to II it is necessary that the screw has sufficient strength and rigidity, in order to absorb the load corresponding to the rolling pressure R, since this load is from the screw before the actual one Pressing the plate between the rollers must be recorded. This method has the disadvantage that the Screw must be made extremely tight.

The aim of the invention is now to provide a hydraulic rolling mill and a method for the hydraulic adjustment of the Specify roll gap in a rolling mill in which the above-mentioned difficulties do not occur.

This object is achieved according to the invention when using a control device of the type mentioned at the outset in that that between the bearing block for the support roller and the housing of the upper roller system for measuring the roller pressure and pressure measuring cells or the like serving to determine the load on the roller system are arranged that further

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A hydraulic cylinder is arranged between the bearing block of the support roller and the housing of the lower roller system, and that finally at least one bendable one that can withstand a significantly lower load than the roller system Detector rod is provided, the load of which is indirectly a measure of a change in position of the lower, vertically movable. Represents the roller system, the hydraulic cylinder in a main control loop as a function of the measured load on the detector rod (s) the measured roller pressure and a reference load on the detector rod (s)

is controllable. The hydraulic cylinder is purposeful moderately controllable in such a way that \

^CP R - ( ^P B - W ■ °>

where C represents a variable that can be selected. Finally, it has proven to be particularly advantageous if a compensation circuit is also provided, which includes a default device for the reference load, a device for preselecting the rolling pressure to achieve the desired thickness and shape, an adjusting device for the roll gap, an adjusting device for the roll level, a device to determine the roll eccentricity, a thickness measuring device and a roll speed meter, and whose compensation signals for error compensation of the entire control system can be added to the signals of the main control loop or can be subtracted from them. 209838/0461

The position of the detector rod or detector rods can, if necessary, be changed. The burden of Detector rod is measured, for example, by means of a pressure measuring cell mounted on top of the rod. By In the compensation circuit, the control signals emanating from the main control circuit are arithmetically corrected so that can achieve a particularly high level of accuracy.

Further features, details and advantages of the invention emerge from the following description of a preferred one Embodiment based on the drawing. Show it:

Figure 1 schematically the already explained above, with Prestressing hydraulic rolling mill in side view;

Figure 2 is a side view of one with the invention Control device equipped hydraulic rolling mill;

FIG. 3 shows a block diagram of the main control circuit and

FIG. 4 shows a block diagram of the entire control device according to the invention.

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-7- 2111508

In Fig. 2, a housing 1 is shown, on which an upper roller 2 is arranged above, which is rotatably mounted in the upper bearing block 3. In addition, an upper work roll 4 is provided, which is rotatably supported in the upper work roll bearing block 5. ^{The lower roll system, which consists of a lower support roll 2 1} in the lower part of the housing 1, a lower bearing block 3 'for the lower support roll 2', a lower work roll 4 * and a lower work roll, is largely similar to this upper roll system consisting of the aforementioned elements. Has bearing block 5 ¹ .

A detector rod 6 is arranged on the front and back of the upper bearing block 3 for the support roller 2, which is flexible so that it can withstand a significantly lower load than the roller system that it penetrates movably in a vertical bore. On each detector rod 6 there is a pressure measuring cell 7 or the like Measurement of the load on the rod and a screw 9, which can be driven by the motor 8, are provided. λ

Also at the top of the upper bearing block 3 for the support roller 2 is a pressure measuring cell 10 or the like for measuring the rolling pressure. The upper bearing block 3 and the upper work roll bearing block 5 are connected to the housing 1 with the interposition of the measuring cell 10 for the rolling pressure ,

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and designed in such a way that they can move the detector rods 6, the lower bearing block 3 ¹ and the lower work roll bearing block 5 ¹ by means of a hydraulic cylinder 13 which is connected to the servo valve 12 via the pressure oil line 11.

The (vertical) change in position of the lower support roller 2 » and lower work roll 4 ', which are movable by means of the hydraulic reducing cylinder 13, is made with the aid of the detector rods 6 detected.

The tensile and compressive load on the roller system is to be determined with the help of the pressure measuring cell 10 to determine the roller load, the change in position of the lower work roll 4 ^f, on the other hand, with the help of the tension or pressure on the detector rods 6, i.e. by means of the load measuring cells 7 *

In order to keep the ratio of the tension or pressure on the detector rods 6 to that on the roller system constant, it works the control device according to the invention such that the oil inflow to the hydraulic cylinder 13 by corresponding Actuation of the servo valve 12 is controlled in accordance with the output signals of the control device.

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2111808

In a hydraulic reducing mill, the thickness h the exiting trajectory is usually expressed by the following equation:

(1)

where S _{Q is} : the initial gap between the work rolls

4 and 4 ¹

Ö _R : load on the roller system ο «: load on the detector rods 6

(This is a measure of the position of the lower rollers)

Of these _{quantities, o R} and ög can be expressed as follows:

(3) i _B = (P _B - P _B0 ) /%

Where P _{R is} : rolling pressure

Ρ «: load on the detector rods 6

Reference load of the detector rods 6, i.e. the force that has to be applied

in order to pretension the detector rods 6 before entry of the web to be processed 209 63 8/0461

K _R : spring constant of the roller system: spring constant of the detector rods 6.

Theoretically it would be possible to set Pg ₀ to the value zero. However, a low load is selected here in order to avoid shaking or displacement between the lower bearing block 3 ′ of the lower support roller 2 ¹ and the measuring cell 7 for determining the load on the detector rods 6.

Putting the values of equations (2) and (3) in the Equation (1), we get:

(4) h = S _Q + P _R / K _R - (P _B -

If P _R and P _{ß are determined} by means of a detector or a corresponding measuring device and C is defined in such a way that it satisfies the following equation (5), then the roller system can be controlled via C.

(P _B -

The following equation is obtained from equations (4) and (5):

(6) h = * S ₀ + (1 / K _R - 0 / Kg) P ₁₁ - S ₀ + P _R / K _e

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K. is bound to the following equation:

(7) 1 / K _e = 1 / K _R -

K_ can be expressed overall as the equivalent rolling mill constant and can be varied by changing C.

For example, if C = Kg / K ^, then it follows from equation (6) that h = S _Q. This means that the thickness h of the ejected web can be kept at a constant value of S _Q (original nip) _{regardless of the magnitude of the roller pressure P R.} This also means that according to equation (7) 1 / K _{Ä is} zero, ie the equivalent

Rolling mill constant K is infinite, which is complete is to be equated with a rigid rolling mill.

3 shows a block diagram of the main control loop according to the invention. Here, K in the block diagram denotes a control amplifier.

In order to obtain the above-mentioned control, the control circuit arranged in accordance with FIG. 4 is integrated into the mechanical arrangement built into the hydraulic reduction unit, which makes it possible to make various settings, to achieve compensation and also to control the servo valve 12.

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In the block diagram of FIG. 4, the circle provided with a cross (on the left-hand side) in each case means a detector or a measuring device, namely A ₁ the load cell 10 for measuring the rolling pressure P _R , Ap and A-? the load cells 7 for measuring the load P _{0 of} the rods 6 at the entrance or exit, A ^ and A, - cylinder pressure detectors, which correspond to increasing or decreasing bending, Ag a device for determining the roller eccentricity, A ₇ a thickness measuring device and A _{Q is} a rolling speedometer. The double circles (right) in FIG. ₄ denote setting or adjusting devices, where B 1 is a device for preselecting the rolling pressure P _R , Bp is an adjusting device for the roll gap, and B ^ is an adjusting device for the roller level and at B ^ is a default device for the reference load Pg ₀ . In the block diagram of FIG. 4, the circles denote adding and subtracting elements, the sign indicating in each case whether addition or subtraction is to be made. A multiplier device is designated by D, which emits a signal at its output which corresponds to the product of the input signals. The transmission of electrical signals is indicated by solid lines, mechanical influence is indicated by dashed connecting lines. Finally, the rectangular boxes symbolize amplifier circles and circles with evaluated constants.

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With RGC and CPR the "roll ^{gap control 11} and the" constant roll pressure control "are designated. K designates a loop amplifier for RGC, K _CpR a loop amplifier for the control of CPR. C stands for a control constant for changing the rolling mill constants, C for a Control constant with a fixed rolling mill constant that is only used in the case of preparation for the rolling process.

K * and Kp are weighted constants.

The setting of the rolling mill constants can be changed by changing C. If C is set manually, the servomotor M rotates and at the same time the loop _amplifier K RGC and the reciprocal size of the equivalent rolling mill constants (1 / K = 1 / K _R - C / Ke>) are also mutually changed.

In the case of the control unit according to the invention, the signal A,. from the cell measuring the rolling pressure P _R to the servo valve 12 via the amplifier circuit C and the loop amplifier circuit K ^ _GC and separately therefrom via the loop _{amplifier circuit K CGR} for constant rolling pressure. The signals corresponding to the load Pg of the rods 6 at the load cells on the input side A ₂ and output side A ₅ are fed subtractively between the loop amplifier circuit and the amplifier circuit C. The signals A ^ and

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which respond to an increasing or decreasing deflection of the cylinder pressure, are fed subtractively with respect to the rolling pressure P _R and the signal A _{1 of} the load cell in the stage preceding the amplifier circuit C. The compensation system is designed so that it _{corrects the reference load Pg 0 of} the rod or rods, with manually predeterminable compensation _{values being formed from the signals coming from the setting device B 2} for the roll gap and the setting device B- for the roll level. Automatic compensation values form the signals coming from the thickness measuring device A ₇ (the gain of this feedback circuit changing as a function of the rolling speed) and the signals from the device A ^ for determining the roll eccentricity. These signals carry out the programmed compensation control by means of the rolling speed in order to correct the change in thickness of the web at the time of the change in the rolling speed (in particular during the start-up and run-down times). A correction is made in order to also prevent a change in the thickness of the web in the event that the rolling mill constant is changed during the rolling process.

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In Figure 4, M 'denotes a servo motor, E a control or. Control element and F a generator, which is a function of the speed or the operating state Signal generated.

The changeover relay contact rlSp should be closed while the preparation for rolling is taking place. The relay contact rls ,. must be kept closed if the control device is to be operated during the actual rolling process. In the case of rolling with regulation of the gap width, the relay contact rls., Must be closed, while in the case of rolling with constant rolling pressure, the relay contact rlSp must be closed.

With reference to the main control operations of the control scheme explained above, the setting of the roll gap, compensations, and changes in the rolling constants are explained in detail below.

1. Adjustment of the roll gap

The roll gap setting, which must be carried out before the start of the rolling work after the roll has been replaced, can be carried out by turning the screw 9 of the rod 6 by means of the drive motor 8 shown in FIG . will.

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By arbitrarily choosing C, the reference _{load Pg 0 is set} with respect to the total of the incoming and outgoing loads Eq of the bar. If the rolling pressure P _R is not yet generated in this case, the hydraulic cylinder 13 can be raised by appropriate control of the servo valve 12 in order to make the rod _{load P 5} equal to the reference load PgQ according to the block diagram of FIG. 4 (the compensation signal system is complete reset) if the push rods 6 are raised by means of the screws. In particular, the lower roller system goes up against the fixed upper roller system, the rolling pressure P _{R being} generated when the upper and lower work ^{rolls 4 and 4 1} come into contact with one another, the control taking place according to equation (5). In this way, Pg changes versus

Either the roll gap is set to zero at this point in time or a corresponding amount of the roll pressure P _{R is} made zero.

Then, by lowering the lower roller system by turning the screws 9, the roller gap is set in this way

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set so that it corresponds to a certain web thickness. In this case, the loads on the rods on the working side as well as on the drive side are equal to Po ₀ »so that the roller can easily be balanced.

In order to prevent the current web thickness becomes greater than the set exit thickness, namely as a result of the roller train after the roller gap has been adjusted to the thickness of the exiting web, the lower roller system is controlled by means of the hydraulic cylinder raised, thereby increasing the width of the roll gap by the size P ^ / Kg according to equation (6) Decrease amount. This value can be calculated with the magnitudes of the rod load as follows represent:

^P B0 - ^P B0

In other words, it just happens that PgQ has occurred instead of PgQ. Of course If the rolling mill constant K and the rolling pressure P «have been set, the regulation according to Equation (8) is carried out automatically by means of the control device according to FIG. 4.

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Even in the case that the upper roller by means of the screw arranged above the center of the housing 1 is driven, the adjustment can be made in the manner described above.

2. Various compensation operations Assume that in the hydraulic reduction mill all compensation signals including '

borrowed the thickness compensation, the compensation of the roller ^ level, etc. are compensation signals to be _{added to the rod load P ß} , by which the position of the lower roller is determined.

The amount of compensation can be represented by the following equation:

(9) ΔΡ _Β =

Δ X means the shift that must be given to the lower roller in order to obtain ΔBq,

In the event that the thickness of the outgoing web is subject to a change due to a change in the roll eccentricity and the thickness of the oil film , the compensation signal for AX is determined by measuring the roll gap and the thickness of the

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Railway through direct application of the thickness measuring device
Ay received. When accelerating or decelerating, the coefficients of elasticity of the web will change, mainly due to the change in the coefficient of friction between the web and the roller and
the change in train is due. As a result, the web thickness will change.

For this reason, a rolling speedometer becomes An used to measure the rolling speed, to which the compensation value A X is then adjusted by means of a function is programmed to compensate for the speed generating generator, so as to change the web thickness to prevent.

The load cell 10 for measuring the rolling pressure determines not only the rolling pressure, but also that on the roller
acting bending forces. As a result, the measurements of the pressure or load cell 10 should be corrected by the bending forces using cylinder pressure detectors A ^
and Ac can be determined. The following applies:

(10) real rolling pressure =

measured rolling pressure - K ¹ χ (bending forces)

Here, K ¹ : weight constant

20 98 3 8/0461

The weight constants for increasing and decreasing bending are indicated by K ₁ and K ₂ , respectively. '<1i 0 <K ₁ <1; 0 <K ₂ <1)

3. Changing the rolling mill constants As the above description makes clear, the equivalent rolling constant (K _e ) can be changed by changing

can be varied by C, which is used to select the types of rolling.

Whenever the coefficient of elasticity of the material to be rolled changes or a weld seam passes through during rolling, or whenever the rolling conditions have to be changed from drive operation to continuous operation and vice versa, the rolling constant K _{e can be} changed, whereby the web thickness aue

is kept constant automatically or manually.

To put it more precisely, since P “q | according to If equation (8) changes, the roll gap can be changed to keep the thickness of the exiting web constant to keep. It should also be noted that in the event that the rolling constant is subject to change 'the control amplifier' is also automatically οine Undergoes change in order to reach an optimal value.

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As a result of the aforementioned special training "resp. Arrangement, the control device for a rolling mill according to the invention is characterized by:

a) Rolling with variable rigidity of the rolling mill:

By selecting C accordingly, the rigidity of the rolling mill can be adjusted so that it is adapted to a special rolling scheme.

r If C is chosen to be Kg / Kj ^ , the rigidity of the rolling mill becomes infinite, which makes it possible to carry out a rolling process with a constant thickness regardless of the thickness of the starting material.

In addition, it is possible to carry out a rolling process with a constant extension, for example E-flat rolling, according to the zero stiffness of the rolling mill.

b) Rapid response to reduction: The vertical movement of the roller system operated a drive system equipped with a servo valve and hydraulic cylinders and its response speed more than

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is ten times as high as with conventional motor-driven systems and more than three times as high higher than with the usual hydraulic systems.

Ί_ As a result, this system as appeal 10 Hz to a cycli- \ metallic interference with such a high frequency.

This also includes the possibility of getting rid of the effects of roll eccentricity, the occurrence of parts that are not dimensionally accurate during acceleration, deceleration or the To reduce the passage of the web and finally j lent the possibility of the meander formation in the case to control the automatic winding of the web, which makes the rolling work much easier overall will.

c) Light thickness compensation:

By changing the reference load Pq _{0 of} the rods, the thickness compensation can easily be carried out, and all other compensations are simply carried out on the basis of ί.

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d) Precise and easy adjustment of the roll gap: The adjustment of the roll gap, which was previously carried out by Dependent on the experience of the operator, it now becomes accurate and easy just by adjustment the thickness of the outgoing web and the rolling pressure.

The fully automatic control of the gap width is feasible if the inlet thickness is Outlet thickness, the width of the web and the type of web in addition to setting the rolling pressure can be specified using a simple arithmetic operator.

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Claims (2)

Claims Control device for adjusting the gap width in hydraulic rolling mills, the lower roller system of which is vertically movable with respect to the upper, fixed roller system, characterized in that between the bearing block (3) for the support roller (2) and the housing (1) of the upper roller system (2, 3, 4) for measuring the roller _{pressure (P R} ) and for determining the load on the roller system serving pressure measuring cells (10) or the like are arranged that between the bearing block (3 ') »the support roller (2 ¹ ) and the housing ( 1) of the lower roller system (2 ¹ , 3 '»4 ¹ ) a hydraulic cylinder (13) is arranged, and that at least one flexible detector rod (6) which can withstand a significantly lower load than the roller system is provided, the load (Pn) of which is indirect represents a measure of a change in position of the lower, vertically movable roller system (2 ¹ , 3 ' _f 4 ¹ ), the hydraulic cylinder in a main control loop as a function of the measured load ung (Pg) of the detector rod (s), the measured roller pressure (P ") and a reference load (Pqq) of the detector rod (s) can be controlled. 209838/0461 2. Control device according to claim 1, characterized in that the hydraulic cylinder (13) can be controlled in such a way that that applies: ^P R - where C represents a variable that can be selected. 3 · Control device according to claim 1 or 2, characterized in that, in addition, a compensation circuit. is provided, which a default device (B ^) for the reference load (Pg ₀ ) * a device (B ₁ ) for preselecting the roller pressure (P _R ) to achieve the desired thickness and shape, an adjusting device (B,) for the roller level, a means (Ag) for determining the roll eccentricity, 'having a thickness measurement means (Ay) and a roll speed sensor (a _Q) and whose Kompensationsssignale are subtracted added up to the error compensation of the entire control system to the signals of the main control loop or of these. 209838/0461 Blank page