SU1682058A1 - Flying shears with velocity-matching mechanism control device - Google Patents

Abstract

The invention relates to mechanical engineering, in particular, to electric drive control systems for flying shears, which perform the cutting of strip material on the move for given dimensional lengths and are equipped with a speed equalization mechanism. The purpose of the invention is to increase the reliability of the device and the performance of the volatile scissors by increasing the engine speed. The device contains electric flying scissors, strip movement sensors, flying scissors speed, engine speed, speed controller and unit length gauge. The unit includes setting and calculating the average velocity, determining the total moment of the amount of movement (angular momentum) of the two-mass drive system. In this case, the oscillation of the speed of the electric motor and the reel shears in each cutting cycle, caused by the action of the speed equalization mechanism, is accompanied only by the exchange of kinetic energy between the two masses without transferring energy from the network and back to acceleration and deceleration of the drive. Energy is consumed from the network to carry out frictional losses and energy losses when cutting the strip material. 4 il. (Ls

Description

The invention relates to mechanical engineering, in particular, to electric drive control systems for flying shears, which perform the cutting of strip material on the move for given dimensional lengths and are equipped with a speed equalization mechanism.

The purpose of the invention is to increase reliability by simplifying the device and increasing the performance of the flying scissors by increasing the speed by reducing the energy loss in the engine crankshaft.

Fig. 1 shows a functional diagram of the device; Fig. 2 shows a functional diagram of a unit for calculating an average drive speed; FIG. 3 shows cyclograms of changes in the speeds of the engine and scissors; Fig. 4 shows cyclograms of a change in the gear ratio.

The device comprises an engine 1 articulated via a speed alignment mechanism 2 with the drums of a flying scissors 3. A motor speed sensor 4 is connected to the engine shaft, and a scissors speed sensor 5 is connected to the shaft of the scissors drums. With strip 6, a speed sensor 8 for the strip is connected by means of the measuring roller 7. The speed reference channel contains the average speed setting block 9, controlled from the setting device 10 of the length. The current regulator 11, the amplifier 12 of power are included in the motor current control loop.

00

u o ate

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engine, motor 1 and current sensor 13. The control circuit of the average drive speed includes a speed controller 14, a motor speed sensor 4 and a scissor speed sensor 5, as well as a unit 15 for calculating the average drive speed. The internal feedback compensation channel for the EMF of the engine contains the EMF compensation link 16, In turn, the average drive speed calculation unit contains the scale links 17 and 18 and the adder 19.

The device works as follows.

With continuous rotation of the drive, the presence of a speed equalization mechanism with a variable gear ratio in the cutting cycle leads to periodic speed fluctuations (the period corresponds to the time of one revolution) of a two-mass electric drive system, the first mass of which determines the inertia moment on the drive motor shaft and scissors drum shaft. The device is based on the regulation of a certain average speed of a two-mass drive system.

The average speed of a rotating system consisting of two masses connected to each other by a gearbox with a variable gear ratio is the angular velocity of a conventional single-mass system, the moment of inertia of which is equal to the sum of the moments of inertia of the components of the system, and the angular momentum (moment of momentum) of this conventional system is equal to the sum of the moments of the amount of movement of both masses of the original system. Mathematically, this definition is expressed by

(J1 + J2) 0) with J1 a) + J2 “2, (1) from where

J2

We,, 0) 1 +,. Jl + J2Jl + J2

ufc,

(2)

where ft) i, - angular velocity, respectively, of the motor shaft and the shaft of the scissors drums;

J i, Ja - moments of inertia, respectively, on the motor shaft and on the shaft of the scissors drums;

(DC is the average system speed.

The unit 15 calculates the average speed of the system based on the output signals of the al and 0) 2 motor and scissor speed sensors using the scale links 17 and 18 and the adder 19, in accordance with expression (2), generates a feedback signal ok when controlling the average speed of the drive.

The cutting of rolled products for given dimensional lengths is carried out by adjusting the required ratio of the average for the cutting cycle, the angular velocity of the drive and the strip speed in accordance with the expression

Shzs (Os 27g-g-,

ABOUT)

where V is the speed of the strip; L - preset cutting length:

Ofec - setpoint average drive speed.

From expression (2), taking into account (3) the angular velocity of the shaft of the scissors drums is equal to

d) 2 (Uzs | L. (4)

"And - The average value of the velocity of the shaft of the scissors snares is determined by the expression

(01s In

B

about

(five)

where t is the period of rotation of the scissors drum shaft.

Substituted in (5) the value of dt -f-, a

30 ™

also taking into account (4), we get

OLS

) zs (1 + L)

2L

/ (1 + A) dp

about

(6)

55

where p is the angle of rotation of the shaft of the scissors drums.

The gear ratio i can be any 40 a function of the angle p, which has an average value of one for one revolution of the shaft. Take, for example, the velocity equalization mechanism, in which

I 1 + A sin p, (7)

 where A is a coefficient depending on a given cut length.

Substituting this value into expression (6), we get

(02s (Oes, (8)

° ie the average value of the angular velocity of the shears corresponds to the required cutting length.

The signal (the is formed in accordance with the expression (3) at the output of block 9

setting the average drive speed, which is a known multiplier-separating device.

With the start of the unit with a band, the signal Shzs increases (for example, linearly) from

zero to some given value. The electric drive accelerates under the influence of a speed regulator ensuring the equality of the set and actual speeds (OC average speeds of the two-mass system. At the same time, the output of the current control signal is supplied to the current regulator input from the speed controller output. In view of the limited speed of the current control loop and the presence of Negative coupling of the motor's emf gives the specified current a certain dynamic error proportional to the rate of change of the emf. To eliminate this error, the current regulator is fed The signal Ек of the positive positive communication on the EMF, formed by the link 16 of the EMF compensation in accordance with the transfer function

J1 (P)

 KE

Tmr

+

,,

where KE is the coefficient of proportionality between the EMF and the angular velocity of the engine;

Tm is the sum of small uncompensated constant times in the current control loop;

 constant filter time.

As a result, the motor current I is maintained equal to the specified 3 and a torque is created on the motor shaft, a variable component of which is proportional to the acceleration of the unit and the total moment of inertia of the drive, and the constant component is determined by friction in the mechanical links. At the moments of cutting the strip, the current control pulses are formed by the control system, which are necessary to create the cutting moment. During the period of acceleration of the unit, the power consumed from the network is converted into the kinetic energy of the rotating two-mass system, and is also spent on overcoming the friction forces and on cutting the strip.

After the end of the acceleration of the unit, the speed of the strip becomes constant and the two-mass drive system rotates with a constant average speed ok equal to the set speed (Oz. Corresponding to the required cutting length. If we neglect the friction and disturbance arising at the moment of cutting, there will be no power consumption from the network. At the output of the speed controller, the current reference signal will be equal to zero and this zero reference will be accurately processed by the current control loop due to the action of the EMF compensation link. voltage

ten

15

20

35

25

30 40 45

50

the power amplifier will follow the change in the EMF of the engine, proportional to its speed. In this case, the dual drive system can be considered as isolated from external disturbances. Such a system has at any time a constant value of the moment of momentum, and the speeds of the rotating masses change in antiphase as a result of the action of internal dynamic forces due to the fact that these masses are interconnected through a gearbox with a variable gear ratio

As for the kinetic energy of the system, it, keeping the average value, varies periodically with the frequency determined by the frequency of rotation of the scissors drums, partially transforming into the potential energy of the elastic deformation of the mechanical links.

Thus, in the elastic device, the alternating sign deformation of the mechanical links is due to the kinetic energy of the rotating masses.

Taking into account the disturbing effects, the regulation of the predetermined average speed of the two-mass system in the device leads to the fact that the speed fluctuations of the engine and scissors drums in each cutting cycle are accompanied only by the exchange of kinetic energy between the two masses without transferring energy from the network and back to acceleration and deceleration of the drive. Only energy is consumed from the network, it is necessary to compensate for frictional losses and energy losses during strip cutting, as well as energy to create (eliminate) the kinetic energy of the electric drive during acceleration (deceleration) of the cutting unit.

Claims (1)

Invention Formula A flying scissors control unit with a speed equalization mechanism containing a drive motor, on whose shaft there is an engine speed sensor, a serially connected current controller and a power amplifier connected through a current sensor to the drive motor, a scissors drum speed sensor, a rental speed sensor, connected to the first input of the set unit of the average speed of the drive, the second input of which is connected to the length adjuster, speed controller, output connected to the first input of the regulator The current of the second input is connected to the output of the current sensor and the third input is connected to the output of the motor EMF compensation link, the input of which is connected to the output of the engine speed sensor, characterized in that, in order to increase the reliability of the device, simplify the design and increase the performance of the volatile components. scissors by increasing the speed of the drive, a unit for calculating the average speed of the drive is inserted into it, and the output of the block for setting the average speed of the drive is connected to the first input of the speed regulator The calculation of the average drive speed is associated with the scissor drum speed sensor, the second input is connected to the engine speed sensor, the output is connected to the second speed regulator input. / J ) 3 ABOUT Figl. -We J phage.I MuMtHtn pftt Phage. 3 i 1 + Allnf W zir