JPS59193709A - Speed control device of rolling mill - Google Patents

Abstract

PURPOSE:To make rolling operation smooth by recovering in a short time the lowering of the number of revolutions of a motor for driving a roll of finishing mill caused by an impact drop phenomenon, at the time when a steel wire rod is rolled by a finishing mill cooled by a cooling pipe, and formed into a ring-shaped product by a laying head. CONSTITUTION:A steel material 1 is finish rolled by a finishing mill 2 and is cooled by passing it through a cooling pipe 3, then is formed into a ring-shaped wire rod product 1' by a laying head 4. In this case, when the material 1 is bitten by the mill 2, the number of revolutions (v) of a roll driving motor 6 is reduced by an extent (DELTAV) of impact drop and is restored to the former number of revolutions after a restoring time TR. At that time, an output voltage of a rotary generator 8 used for a speed detecting circuit of the motor 6 is inputted to the speed detecting circuit 15, and an actual speed VFB of the motor 6 and a reference speed VREF are inputted to a speed control circuit 9, to compare both speeds with each other thereby outputting a current reference IREF in accordance with the speed deviation obtained from said comparison. At the same time, a reference V'REF is continuously outputted from a speed reference switching circuit 16 to the circuit 9, to restore the number of revolutions of the of motor 9 to the former one in a short time thereby operating the rolling smoothly.

Description

TECHNICAL FIELD OF THE INVENTION The present invention relates to a speed control device for a rolling mill, and more particularly to a speed control device for a rolling mill for steel wire equipment.

Technical background of the invention Figure 1 shows the structure of the construction, and shows the flow of material (in the direction of the arrow).
The configuration will be explained according to the following.

Material 1 is rolled in finishing mill 2 with a pressure of yA J&, and after passing through finishing mill 2, it passes through water cooling @3 which cools the material.
The material 1 reaches a rain head 4 that forms the material 1 into a ring shape, and is discharged from the rain head 4 to become a product l'. The rolling machine 6 whose speed is controlled by the power converter 7 is mechanically directly connected to the finishing mill 2 via the gear 5.
is moving away.

A tachometer generator 8 is attached to the mechanical shaft of the electric motor 6 to detect the speed of the electric motor 6.

Here, the speed of the rolling machine 6 is controlled by the eye force conversion device 7, but when the tip of the scraping material 1 gets caught in the finishing mill 2, the speed of the rolling machine 6 changes as shown in FIG. Indicate a phenomenon.

This phenomenon is generally referred to as an impact drop phenomenon, and the load torque that is applied as a disturbance to the speed control system that controls the motor speed causes a step penalty, and even though speed control is being performed, transient It refers to causing a change in speed,
This is the case when the tip of the material 1 gets caught in the finishing mill 2 described above.

Figure 2 is a speed variation diagram for impact loads with motor speed V on the vertical axis and time on the horizontal axis.
Finishing mill 2 with C]! : The tip of material 1 is bitten, and the drive machine 6
Since the generated torque cannot follow the load torque required by the finishing mill 2, as shown by the solid line, the time t1 to tJ
8Hc], the speed of the motor 6 is reduced. Next, between t and t, [5EC], the original speed is finally shown by a broken line. Speed reference value 2 of power conversion device 7 Traction machine 6
This indicates that the speed of

Time t1 until the speed of this motor 6 decelerates and ends acceleration
~t, [SEC] is called the recovery time TR, and considering the stability of the speed control system including the mechanical system, it is approximately given by the following equation.

5 to 7%-wc [SEC] (11 where Wc: response speed of speed control system [vad/81,
The impact drop amount ΔV, which is the maximum value of the speed drop, changes depending on the speed control response of the GD2 rolling mill, the rolling torque required to roll the material, etc., and is given by the following equation.

60 1 0.85 △"""2 w "Gl)""■"L (
21 Here △V: Impact drop] rr, p, m]
GD2: Gy [~・d] of the rolling mill, etc. Wc: Speed response of the speed system including the rolling mill [vad/5) TL: Rolling torque (N - m') Recovery expressed by equation (1) If the time TR is very short, the impact drop amount shown by equation (2) is small, and the speed change is negligible in the rolling operation,
Although this is not a problem, in reality, the following problems occur due to mechanical system constraints, such as the inability to increase speed control response due to the drive mechanism using gears.

Problems with the Background Art As shown in Fig. 1, material 1 is rolled in finishing mill 2, but even though the rolling speed is high, the impact drop recovery time T is long, so the tip of material 1 is rolled. Finishing mill 2
It is when the recovery time TR has not yet elapsed that it gets stuck in the finishing mill 2 and enters the water-cooled pipe 3.

Therefore, while the tip of the material l is moving inside the water-cooled pipe 3, the motor 6
The speed of is an acceleration operation between t2 and t3 [sEc] as shown in Figure 2, and a force that suddenly acts forward (as if pushing forward) is applied to the thin material that is moving at a controlled rate in the water-cooled pipe. Since there is water in the water-cooled pipe, a resistance force due to water (secondary force) also occurs.

As a result, sudden changes in water resistance within the water-cooled pipes can affect the rolling mill, resulting in misrolls.
This not only involves discarding misrolled materials, but also causes problems such as clogging the water cooling pipe, which hinders smooth photographing.

Therefore, in order to eliminate the misroll, the conventional device attempts to eliminate the above-mentioned impact drop phenomenon as follows.

First, Fig. 3 is a speed fluctuation diagram of the drive machine 6 with the speed V of the motor 6 and the speed reference R1LF of the power converter 7 on the vertical axis and the time t on the horizontal axis. , the speed reference VR1iF is shown by a broken line.

As shown in FIG. 3, the speed standard of the power modulation device 7 that controls the speed of the electric motor 6 is corrected standard value △■ corresponding to the impact drop angle ΔV predicted by the above-mentioned equation (2) in the 8th edition. In addition, the speed V of the magnetic motor 6 is increased in advance.
At the same time as the tip of the material 1 enters the finishing mill 2, the above-mentioned correction reference value ΔV' is made zero.

The timing at which the tip of material 1 enters finishing mill 2 (time t, Csgc) is not shown in the figure, but the tip of material 1 is tracked using the speed of the upstream stand of finishing mill 2 and the material detector. is being detected.

However, compared to the case shown in FIG. 2 in which no correction reference value is added, the generation of the force pushing the material 1 forward is somewhat smaller, but it still cannot be avoided and becomes a problem.

Therefore, material 1)a- In order to avoid the generation of force pushing forward, the correction reference value of the speed reference VRIIF is changed to the correction reference value (2) above.
Equation (2) It is possible to set the value to be larger than the predicted impact drop amount △V, but in that case, the motor 6
The speed changes as shown in FIG.

Note that the horizontal and vertical axes in FIG. 4 indicate the same things as in FIG. 3.

As shown in this figure, by increasing the value of V' to the correction standard, it is possible to avoid the force that pushes the material 1' and forward, but if the sleeve is too large, the quasi-value △V'
In addition to the original speed standard VREF, this becomes a big problem in multi-strand rolling where multiple pieces of material are simultaneously rolled in the same rolling mill.

Purpose of the Invention The present invention has been made to solve the above-mentioned problem, and provides a rolling mill that can avoid applying forward force to the tip of the material in the water-cooled pipe and can operate smoothly. The purpose of the present invention is to provide a speed control device.

SUMMARY OF THE INVENTION An object of the present invention is to switch the speed reference of the electric motor to the rotational speed fed back from a speed detection circuit provided in the electric motor that drives the rolling mill when the rolling mill bites the rolled material and causes an impact drop; This is achieved by the speed control device of the rolling mill which returns the speed reference of the electric motor to the speed before the impact drop m after a predetermined period of time has elapsed.

Embodiment of the Invention Hereinafter, an embodiment of the present invention will be described with reference to FIG.

FIG. 5 shows the circuit configuration of a speed control device that controls the speed of the electric motor 6 that drives the finishing mill 2. As shown in FIG.

Note that this speed control device 111 corresponds to the gravity conversion device 7 in the above-mentioned explanation of conventional string making.

The output voltage of the tachometer generator 8 attached to the shaft of the electric motor 6 is input to the speed detection circuit 15, and the output voltage from this circuit is the speed feedback vF indicating the actual speed 2 of the motor 6.
Speed standard VRE that shows all the desired speeds of B and electric Jfi6
F is input to the speed control circuit 9.

The speed control circuit 9 compares the two and outputs a magnetic current reference 111EF corresponding to the speed deviation.

Then, input the current from the shunt 13 provided in the circuit connected to the Tonisogo of Shido Shin 6 to the heart flow detection circuit 14,
The drive a! Magnetic current feedback IPN indicating the actual seismic flow value of 6 and the above-mentioned current reference IR
EF is input to the current control circuit 10.

The magnetic current control circuit IO compares both of them and outputs a phase control signal PH7 corresponding to the current deviation.

The phase control circuit 11 inputs the above-mentioned phase control signal PH,
The firing phase of the thyristor 12 is controlled, the DC voltage of the armature circuit of the motor 6 is increased, and the speed of the clay movable maple 6 is controlled.

Therefore, when the tip of the material 1 is placed in the finishing mill 2, the load torque exerted on the electric motor 6 increases, and the speed of the electric motor 6 temporarily decreases.

When the speed decreases, the tailflow reference IREF, which is the deviation output of the speed control circuit 9 described above, increases, increasing the electric PA60 tonnage tailflow and increasing the speed of the electric motor 6, thereby increasing the speed reference VRE.
It is controlled to be equal to F.

In other words, the torque generated by the electric motor 6 follows the variation in the load torque of the raw motor 6 with a delay of the speed control response delay time.

Therefore, the speed feedback VFBY is input to the speed reference switching circuit 16, and although it is not shown in the figure, the finishing mill 2
The tip of the material 1 is tracked using the speed of the upstream stand and the material detector, and when the tip of the material 1 bites into the finishing mill 2, the contact 17 is fully closed, and the speed reference circuit 16 provides speed feedback to the speed control circuit 9. The value yxh equal to vFB and the rewriting standard ■RIP' are continuously output.

At the same time, the speed reference ■R8F of the speed control circuit 9 is continuously updated to the value of the replacement reference vR11F'.

Therefore, in the speed control circuit 9, the speed reference and speed feedback values that were being compared become equal, and the deviation becomes zero.

In this way, by reducing the deviation of the speed control circuit 9 to zero from the time when the tip of the material 1 is bitten into the finishing mill 2, the magnetic current reference "RKF" becomes zero from that point on, and the magnetic current 1st & 6th turtle machine The turtle flow is controlled to maintain the current value.

On the other hand, the speed of the electric motor 6 will decrease by the increased load torque, but as long as the speed feedback value is always the speed reference value as described above, the mortar flow for acceleration will not increase. , the speed V of the motor 6 is maintained at a reduced speed as shown in FIG. 6, and the speed V of the electric motor 6 is not accelerated.

Although not shown in the figure, the tip of the material 1 is tracked using the speed of the finishing mill 2 and the material detector, and the contact 17 mentioned above is opened at the timing when the tip of the material 1 comes out of the water cooling pipe 3. .

When the contact 17 opens, the speed control circuit 9 changes to the current speed reference V.
When the igr"l contact 17 is closed (2), the i8 degree reference value is transferred to the previously stored return Jlf reference VR,.

Although the example describes the case where there is material in the water-cooled pipe, with this device, no matter where the material position is, only the timing of changing the speed reference yx* can be changed to accelerate the motor acceleration wM. I can do it.

Effects of the Invention As described above, according to the speed control device for a wire rod rolling mill of the present invention, it is possible to avoid acceleration of the speed of the rolling mill when the material is bitten in the rolling mill (2. It also avoids misrolls that are common in conventional systems, allowing for smooth operations.

The present invention is particularly effective in multi-strand rolling where a plurality of materials are rolled in the same rolling mill.

[Brief explanation of the drawing]

Figure 1 is a diagram of the configuration of the wire equipment, Figure 2 is a diagram of speed fluctuations with respect to impact loads, Figure 3 is a diagram of speed fluctuations of a motor with a conventional device, and Figure 4 is a diagram of motor speeds with a conventional device when the correction standard is increased. Speed fluctuation diagram, ′! FIG. JI5 is a circuit configuration diagram of a speed control device according to the present invention, and FIG. 6 is a speed fluctuation diagram of an electric motor according to the present invention. l Material 2 Finishing mill 3 Water-cooled pipe 4 Laying head 5 Gear
6 @Motor 7 Magnetic force conversion device 8 Tachometer generator 9 Speed control circuit IO free flow control circuit 11 Phase rigidity circuit
12 Sai9 star 13 Flow divider 14
Current detection circuit 15 Speed detection circuit 16 Speed reference switching circuit 17 Switching contact signal (7317) Agent Patent attorney Noriyuki Chika (and 1 others)
Figure 1 Figure 2

Claims (1)

[Claims] Drive the rolling machine! kl+Tru' A rolling machine, a speed reference given so that the motor rotates at a predetermined speed, and a speed detection circuit that detects the northness of the motor, the cutting pressure! Speed reference switching that changes the bq speed reference to the reduced speed of the motor detected by the speed detection circuit when the machine A bites into the rolled material, and switches again to the nij speed reference after a predetermined period of time has elapsed; A salinity control device for a rolling mill, comprising a circuit.