SU766688A2 - Bed forming method in reversible hot rolling mill with individual roll drive - Google Patents

Description

(54) METHOD OF SKI FORMATION INGOT ON REVERSIBLE

MILLING CUSTOM WITH INDIVIDUAL

DRIVE ROLLER

I

The invention relates to automating the process of metal rolling on blooming reversing mills such as blooming, slabing, as well as heavy-duty rolls with an individual electric drive.

A known method of automatically changing the absolute mismatch of the speeds of rotation of the rolls according to the main author. St. No. 528974 by reducing this misalignment with an increase in capture rate above a given value and an increase in this mismatch at a capture rate below a predetermined value, and the relative mismatch of the roll rotation speeds are automatically adjusted inversely proportional to the square of the capture speed by changing the absolute mismatch of the roll rotation speeds inversely proportional to the capture speed.

The disadvantage of this method is that with a significant change in metal sections during the rolling process, when both the height and the width of the workpiece change, for example blooming, it is often necessary to manually adjust the misalignment of rotation speeds of the rolls as a function of the cross-sectional dimensions in the pass.

Indeed, it is known that the bending moment M is determined by the expression

,

where o is the yield strength; in - the width of the workpiece; h is the exit height of the workpiece (thickness).

In this case, due to the relatively small change in the temperature of the workpiece in the cycle of reductions, the change in the yield strength can be neglected compared to the change in the height (thickness) of the workpiece.

In order to increase the accuracy and reliability of the mill operation, the described method additionally measures the width and thickness of the workpiece and the signal proportional to the thickness of the workpiece is squared, multiplied by a signal proportional to the width of the workpiece 20, and the resulting product corrects the signal proportional to the mismatch of rotation speeds rolls, which vary inversely with the capture speed.

The drawing shows schematically a device for implementing the described method of ski ingot formation.

It has a potentiometer 1, which sets the signal proportional to the velocity error, the resistor 2 is input for the master signal, the amplifier-adder 3 nonlinear operational with output 4, the upper roller speed sensor 5, the potentiometer 6 for correction of the velocity error signal, the comparison potentiometer 7, the rectifier 8 comparisons, a resistor 9 input for a correction signal, a W resistor in the feedback circuit of amplifier-resistor 3, a ski-off switch 11, a current sensor 12, resistors 13 and 14, limiting transistors 15 and 16, the capacitor 17, the resistors 18 and 19, respectively, regulating and limiting, the Zener diode 20, the resistors 21 and 22, respectively, are discharge and noise-suppressing, the diodes 23 for tuning away from dynamic currents.

The device further comprises a sensor 24 for positioning the upper roller 25, a quad 26, a multiplier 27, sensors 28 for moving the ruler arms 29, an integrator 30, a source 3 for a reference signal proportional to the maximum distance between the rulers 29, limiting block 32, at the output which receive the error signal of the rotational speeds of the rolls supplied to the control system (not shown in the drawing).

To disable the integrator 30 after the contact of both rulers with the workpiece is block 33 of the shutdown.

The device works as follows.

In the case of the capture speed, the setting voltage C, proportional to the mismatch of the rotational speeds of the rolls, from potentiometer 1, through the resistor 2, is connected to the input of the amplifier -cumulator 3 ,. the output 4 of which is connected., is chyuchen to the input of the block 32 for limiting the regllor of the speed of the motor Pizhne1) of the roll (not shown). Due to this, the speed .o "of this roll exceeds the speed of the upper roll with, because of the necessary skiing.

The specified speed difference A s, set for the lowest capture rate, has the largest absolute value.

With an increase in the capture rate, the voltage at the output of the speed sensor 5 and potentiometer 6 becomes the reference voltage Ue at the output of potentiometer 7 connected to the input of the comparator 8 of the comparison.

In this connection, through a resistor 9, a signal is supplied to the input of the amplifier-adder 3, the polarity of which is the opposite polarity of the independent error signal Dose. In the above example, in the nonlinear operational amplifier-adder 3, the following signals are algebraically summed: an independent control signal proportional to the mismatch of the rotational speeds of the rolls D with for

the lowest capture rate, a counter-directed signal proportional to the capture velocity osj, but equal in magnitude, with the minimum capture velocity, the Leo value. Moreover, due to the presence of a nonlinear element in the amplifier adder 3, the signal from the speed sensor 5 directly dependent on the capture rate is modified into a special hump-shaped signal, giving in total with an independent control signal connected to the input resistor 2 of the amplifier adder 3, the required hyperbolic law of variation of the mismatch of the rotational speeds of the Aso rolls. In the drawing, the forward signal is a speed-independent signal of the disagreement (Lee), supplied to the resistor 2 of the input amplifier - accumulator 3 from potentiometer 1; direct is a counter-directed to the first signal and a signal depending on the capture rate, which is fed to the resistor 9 of the input amplifier —Su.M.Mator 3 from the output of the speed sensor 5; curve c represents a modified curve in the amplifier-adder 3 non-linear element. Curve d is the desired result of P1 hyperbolic dependence between the absolute difference in the rotational speeds of the rolls Yes and the trapping speed CJj. supplied from the output 4 of the amplifier-accumulator 3 to the input, block 32 of the limit.

In this device, noc, i.e., the ski turbulence scientific research institute carries out the speed mismatch signal.

In the considered example, for these purposes, the feedback resistor 10 of the amplifier — sush.matter 3 is connected to the output of the ski-forming shutdown unit 11.

When a current appears in the power circuit of a rolling electric motor, a voltage appears at the output of current sensor 12, however, the current flow through transistors 15 and 16 is delayed by the time required for the completion of skiing using a capacitor 17, resistors 18 (controllable), and 19 (limiting) and zener diode 20.

For discharging capacitor 17 and preparing the circuit for the next pass, resistor 21 is the discharge resistor, and for protection against interference, resistor 22 is anti-noise, diodes 23 are necessary for tuning from the dynamic current.

Claims (1)

After the billet is seized, the crust current of the rolling motor and the capacitor 17 charge appear, the transistors 15 and 16 open and shunt the resistor 10 of the amplifier - summator 3, therefore, after the completion of skiing, this amplifier voltage and engine speed mismatch becomes zero. To take into account the geometric dimensions of the workpiece, which determine the moment of its bending during skiing (see Expression 1), from the sensor 24 of the position of the upper roll 25, a signal proportional to the thickness h is fed to the input of the square 26, the output of which is connected to one of the outputs of the multiplication unit 27. From the outputs of the sensors 28 of the speed of movement of the ruler lines of the manipulator 29, signals (of the same sign) are fed to the input of the integrator 30, which also receives the reference counter source 31, which is proportional to the maximum possible distance between the rulers. When the rulers touch the workpiece from the corresponding impulse, for example, from the unor current of the ruler electric motors or from the initial negative acceleration signal of the rulers (when they come into contact with the workpiece), the input signals of the integrator 30 are disconnected for the time of metal rolling in this pass using the off block 33, for example by shorting the inputs of the integrator 30. At the same time, at the output of the integrator, a signal equal to the difference between the maximum possible distance m is obtained and stored for the required time. waiting rulers and the magnitude path traversed by both rulers until touching them with the workpiece, m. e. proportional workpiece width. This signal enters as the second multiplier in multiplication unit 27, as a result of which, at the output of multiplication unit 27, a signal is obtained that is proportional to the product of / c –h (where k – D), i.e. the moment of plastic bending of the metal. This signal as a correction voltage is fed to the input of the limiting unit 32, where the signal from the output 4 of the amplifier-sump 3 is supplied, which is proportional to the constant difference in the kinetic energy reserve of the vertical and lower lines: rolls before the seizure of the workpiece. The indicated constant difference between the kinetic energy of the lines of the upper and lower rolls, which determines the dimensions of the ski for a given cross-section of the workpiece, is achieved by changing the mismatch of the rotational speeds of the upper and lower rolls in inverse proportion to the capture speed. The block 33, which determines the mismatch of the rotational speeds of the rolls before the capture, not only ensures the constant difference in the kinetic energy reserve of the upper and lower rolls, but also takes into account the moment of plastic bending of the workpiece. Consequently, the dimensions of the skis are automatically maintained as specified regardless of the grip speed and cross section of the workpiece. It should be noted that the preparation of the inputs of the integrator 30 for the next pass and the reset to zero of the output voltage of this integrator memorized for a given pass, proportional to the width of the workpiece, is carried out using the static current relay contacts not shown in the drawing. The invention The method of ski formation of an ingot on a hot rolling reversing mill with an individual roll drive according to ed. St. No. 528974, characterized in that, in order to increase the reliability and accuracy of the mill, the width and thickness of the workpiece are additionally measured and the mismatch of the speeds of rotation of the rolls is corrected, which is inversely proportional to the capture speed in accordance with the expression M b, where b is the yield strength; in - the width of the workpiece; h - height (thickness) of the workpiece.