DE1527761B2 - Device for the operational compensation of the change in the crowning of the work rolls of a rolling mill - Google Patents

Description

By appropriate programming of the computer 20, the for the production of an essentially Achieve the required control of the correct starting product. With the help of the computer, the Overall operation of the rolling train 10 can be controlled, including control of the rolling speed Via the signal lines 24. Also the already mentioned strip tension control and other possibly provided The computer can take over regulation or control.

To achieve the desired output signals, the computer input can be used in addition to the output thickness signals further signals derived from the variables which can be changed at the beginning of the rolling process are input, for example from the Engine speed derived signals via the signal lines 26. The output signal of the computer 20 can also depending on a data input device, for example a commercially available punch tape reader 38, or controlled as a function of a manual input device 40, with whose help the properties of the respective strip to be rolled can be entered. Possibly intended operational interruptions can also be programmed in the computer 20. The initial dates For the entire computer program, thickness, length, temperature, width (which directly determine the roll deflection determined) and include the type of material of the workpiece to be rolled.

The roll crown as a factor that determines the crown of the strip is contained in the computer program. Flat-rolled rolling stock can therefore be produced with the desired thickness and crown. By doing The extent to which the crowning of the work rolls 12 changes in each roll stand can be determined by the roll adjusting device by the computer via the control signal line 28 to adjust the employment and setting of the Work rolls are operated in the sense of the required band crown.

In Fig. 2 the work and backup rolls are shown on a larger scale. The diameter D ₀ in the middle of the work rolls 12 is larger than the diameter D _e at the ends of the rolls. The rolling force F is transmitted to the work rolls 12 by the backup rolls 14. Half of the total rolling force acts at each end of the back-up rolls 14 and the total rolling force is transmitted to the work rolls 12 via the contact surface between the work rolls 12 and the back-up rolls 14.

The original roll crown before insertion the work roll is well known.

For operational measurement of the crowning of the work rolls, the total rolling force in the case of a "negative" Roll gap measured, d. H. the work rolls are first brought into contact, then the Adjusting device actuated in the same way and the resulting force measured.

The values of the rolling force F and the “negative” roll gap X are taken when there is no rolling stock between the work rolls 12. These values therefore result in a characteristic elongation curve for the roll stand. As an example, Fig. 3 shows the expansion characteristics of a stand of a 3.4 meter heavy plate mill.

The roll crowning is measured first with new work rolls 12. This results, for example, in the figure shown in FIG. Characteristic curve 42 shown in FIG. 3. The rolling force and the roll gap are determined by corresponding signals on lines 30 and 32. The zero point of the characteristic curve is determined by the contact between the work rolls. The rolling force F increases non-linearly as the roll gap becomes increasingly "negative" until the play in the adjusting spindles and in the stand is eliminated. From point 46 on, the ratio between the rolling force and the roll gap then becomes constant. During this initial measurement, the rolling force is measured up to an arbitrarily chosen value,

ίο, for example, 1000 tons (reference number 48) increased. The corresponding roll gap is in Fig. 3 with -2.5mm specified.

In the case of a straight course, the characteristic curve would intersect the X-axis at point 57, as shown by the dashed line. The distance Xsi is determined by different sizes, for example the play in the adjusting spindles and in the frame and the different deflection of the work and back-up rolls. The change in the non-linear part of this characteristic is essentially the basis for determining the change in crowning.

After the work rolls 12 have been put into operation, the elongation characteristic can be renewed at certain time intervals determined and from this the change in the roll crown can be determined. This measurement can be quick be carried out between the rolling steps. For example, a new measurement is made after two Operating hours or when it can be assumed that the work roll crown will be, for example Result of different rolling temperature has increased, carried out and so a new strain curve 50 determined. This results when the rolling force reaches the selected value of 1000 tons (reference number 52), the roll gap Λ52 to - 2.75 mm. The change of the roll gap results in

AX = xm - X ₅₂ = - 2.5 - (- 2.75) = 0.25 mm.

On the other hand, the change in roll crown is given by:

(Dc-

because it can be assumed with certainty that the overall change determined by the method described the roll crown is approximately equally distributed over the two work rolls 12

At a later point in time during operation, when it can be assumed that the work roll crown has decreased as a result of wear and tear, a further measurement can be carried out to determine the elongation characteristic are made (reference number 54). When the rolling force is the chosen value of 1000 tons is reached (reference numeral 56), the associated roll gap x »is detected and results in this case - 2.25 mm. Then the change in roll crown is

V ₂ ■ [-2.5 - (- 2.25)] = -0.125mm.

The minus sign indicates a decrease in the roll crown from the original value.

The crowning measurement can be carried out as often as required during the Operation of the roller train can be carried out. It can also be done by hand and the results can be done by the rolling mill in a non-computer controlled Roller train to adjust the adjustment are evaluated, so that the desired band crowning can be maintained if the roll crown changes during rolling. The measurement results can also be used to operate a

ΙΟ ΔΙ / oil

analog control device to correct the employment are evaluated.

In the embodiment according to FIG. 1, the computer 20 can be programmed so that he Crown measurements on the individual roll stands and at different times during the rolling operation carries out The values of the strain curve recorded in the process are saved in the computer. if the change in roll crowning for each stand, as described above, is determined, a new one is available Roll crowning parameters are available so that the values to be supplied by the computer for the individual Roll stands can be brought up to date. The computer 20 gives the adjusting device 18 via the signal line 28 before a setpoint value in such a way that the change in the roll crown is compensated will. For this purpose, the computer 20 can, for example, contain a program that has the following for each The equation used in the mill stand includes:

F = 0ds h + kr) Fr.

In it mean

h initial thickness of the strip
As desired percentage crowning of the band
k _r roll crowning determined by measurement
_For spring value for the roll deflection.

F force required to produce a roll deflection that is sufficient to increase the roll crown and also to achieve the desired crowning of the belt.

The value k _r determined for each roll stand causes changes in the rolling force setpoint at the corresponding roll stand. For adjusting the rolling force and for computer-controlled compensation of the

ίο changes in crowning, the inclination is changed. Viewed overall, the computer 20 writes the respective pass schedule for the successive ones Roll stands in accordance with the input properties of the workpiece and controls the Thickness decrease at each roll stand, so that essentially the desired initial thickness is achieved is, while the strip crowning is evenly maintained on the various roll stands and in this way a tailor-made starting product is achieved.

The expansion constant of the roll stand can change as a result of the wear on the backup rolls 14. There the back-up rolls have a service life of one week or more can be assumed to be safe, that the decrease in the elongation constant over the relatively short time in which the comparative Measurements made for the work rolls are essentially constant.

1 sheet of drawings

Claims (3)

Patent claims: 1. Device for the operational compensation of the change in crowning of work rolls a roller train controlled by a computer, characterized in that at least one point each of the expansion characteristic of the, which is dependent on the crowning of the work rolls Roll stand is recorded that in a first measurement after the onset of a new work roll pair and in at least one second measurement after a specified operating time in each case in a manner known per se the employment with an empty roll gap up to one arbitrarily selected rolling force that is the same for both measurements and that of crowning corresponding measured value as a parameter of the strain curve to the computer for operational Correction of the pitch setpoint is entered. 2. Device according to claim 1, characterized in that the measurement of the by the computer Strain characteristic points is triggered periodically. 3. Device according to claim 1 or 2 for the multi-column rolling mill, characterized in that that the change in crowning is recorded individually for each stand by the computer. The invention relates to a device for operationally compensating for the change in crowning of work rolls of a roll train controlled by a computer. Such a device is known from US Pat. No. 3,248,916. To compensate for a change in Roll crowning is introduced into the program for the computer, a correction factor, which consists of a empirically determined equation is derived on the basis of visual observation of existing bumps. Since the correction factor is only an estimated value, it cannot be a perfect one with this device Compensation for changes in the roll crown can be achieved. The invention is based on the object of detecting operational changes in the roll crown and to compensate for them by making appropriate changes in employment. According to the invention, this object is achieved in that at least one point each of the Crowning of the work rolls dependent expansion characteristic of the roll stand thereby added is that in a first measurement after the insertion of a new pair of work rolls and in at least a second measurement after a predetermined operating time in a manner known per se Adjustment with an empty roll gap up to an arbitrarily selected rolling force that is the same for both measurements move and the measured value corresponding to the crowning as a parameter of the elongation characteristic Computer for operational correction of the pitch setpoint is entered. With the measure thus claimed, it is achieved that the operational changes in the crowning of the rolls are measured and compensated for by corresponding changes in the roll adjustment in their effect on the crowning of the rolled strip.
The change in crowning is advantageously recorded individually for each stand by the computer. From DE-PS 9 59 996 a device is known by changing the strain curve a roll stand, which is based on changes in hardness, elasticity and / or the dimensions of the incoming ίο rolling stock are to be taken into account. For this purpose, when the characteristic curve changes, the rolling pressure and the roll gap are increased by one Factor increased or decreased, which is 2 to 8% larger than the respective one that determines the employment Expansion of the roll stand is a deviation of the thickness of the rolled stock from the target value taken. Consideration and compensation of a change in crowning of the work rolls are but not provided. On the basis of an embodiment shown in the drawing, the invention is described below described in more detail. It shows F i g. 1 as a diagram of a computer-controlled rolling mill, F i g. FIG. 2 is a view of a set of the components shown in FIG. 1 used work and backup rolls and F i g. 3 schematic expansion characteristics of a roll stand.
In Fig. 1 shows a rolling train 10 which contains a number of roll stands S1, S2 to 56. Each roll stand is provided with a pair of work rolls 12 and a pair of backup rolls 14 for processing the rolling stock 16, e.g. B. a hot-rolled strip. The rolling train 10 can also be used for rolling other plastically deformable materials and other profiles, such as plates, slabs, etc. Motors 17, for example DC motors, drive the rolls 12 and 14 of each rolling stand using a known speed control. Each roll stand is provided with a roll adjusting device 18 for influencing the support rolls 14 exerted rolling force and thus to control the thickness and crowning of the work rolls 12 continuous strip 16 and equipped with a device 19 that detects the rolling force. The rolling force is adjusted in a known manner so that a substantially constant through dk roller adjusting device ter, predetermined roll gap is maintained. The band crowning is achieved by adjusting the roll gap controlled in such a way, from which the roll deflection unc thus that for the desired crowning of the band required roll crown results. In addition, a known regulating device for the belt can be closed. be provided, in which the speed of the motor to maintain the desired tractive effort can be. Each roller adjusting device 18 is in this embodiment by a central, digita working process computer 20 in connection with analog-digital and digital-analog converter ge controls. In the computer 20 of each adjusting device 18 for calculating correction evaluate for the roll adjustment from the roll anste! development and the rolling force derived signals via di Lines 30 or 32 and also a signal input from one that monitors the output thickness Facility, e.g. B. from a working with R. X-ray thickness measuring device 22 supplied throws