JPS628384B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a tension control device for strip steel in a loop storage facility in a continuous strip processing line.

Continuous steel strip processing line (hereinafter referred to as processing line)
In the above, the loop storage facility is installed between two adjacent sections operated at independent line speeds, and is installed as a buffer facility for strip steel when the operating speeds of the respective sections are different. This loop storage equipment is called a loop car or a loop tower depending on the processing line equipment, and is generally called a looper. The following explanation uses a loop car as an example.

FIG. 1 is a schematic diagram of a processing line including front and rear equipment centered around a loop car. The entry bridle 11 defines the line speed of the entry section, and the exit bridle 12 defines the line speed of the exit section. The steel strip 13 is connected from the entrance bridle 11 to the loop car 14 and the exit bridle 12.
It passes in this order. There is a processing facility ahead. The line speed of the entry section and the line speed of the exit section, ie, the speeds of the entry and exit bridles, are independently determined for the convenience of each operation. For example, if the speed of the incoming section is faster than the speed of the outgoing section, the loops of the strip stored in the loop car 14 will increase. In order to suppress mutual interference between the stored steel strips and torque fluctuations in the front and back of the loop car 14, the loop car 14 is controlled so as to always apply a constant tension to the steel strips stored in the loop car 14. Therefore, in the case of the above example, it is necessary to control the loop car 14 so as to increase the stored steel strip while applying a constant tension to the steel strip.
The control of the loop car 14 will be explained below with reference to FIG.

The loop car drive motor 15 is connected to a variable voltage power supply 2
A current detection circuit 22 is connected to the loop car motor 15 to detect the main current of the loop car motor 15, and compares and amplifies the output of the current detection circuit 22 with a current reference provided from the outside, and uses the output to detect the main current of the loop car motor 15.
It is driven and controlled by a current control system comprising a current control amplifier 23 that adjusts the output voltage of the output voltage. The current reference consists of three elements. The first element is the current value required to apply tension to the steel strip, which is the tension current standard 2 in Figure 2.
It is represented as 4. The second element provides an acceleration/deceleration current and a friction current necessary when the loop car 14 moves, and is similarly provided as a compensation current reference 25 in FIG. 2. The third element is an output from the speed limiting circuit 26 to prevent the speed of the loop car 14 from abnormally increasing in the event that the steel strip breaks due to excessive tension, and is normally given as a current reference via a direction determining diode 27. It will be done. An inlet speed reference 28, an outlet speed reference 29, and a bias 30 are applied to the speed limit circuit 26 with the polarities indicated by the symbols shown in the figure. Signal is connected. In controlling the loop car 14 configured as described above, the loop car 14 is controlled as follows. That is, when the speeds of the input and output sections are normally operated in synchronization with each other, the loop car 14 is stopped because the flows on the input and output sides of the loop car are balanced. In this case, the loop car 14 is controlled such that its current is the value of the current reference given by the tension current reference 24.

Next, once the balance between the entry and exit sides is disrupted,
The loop car 14 needs to move according to the speed difference. The compensation current reference 25 is given to compensate for the torque of the loop car 14 during acceleration/deceleration or running at a constant speed, and is generally compensated for in terms of acceleration/deceleration torque and traveling friction torque. As already mentioned, the speed limiting circuit 26 is provided to prevent the loop car 14, which has lost its restraint by the steel band, from overspeeding when the steel band breaks or the like. In other words, entry speed standard 2
When the output from the speed detector 31 becomes larger than the difference between the speed reference 8 and the exit speed reference 29 plus the bias 30, the deviation is amplified by the speed limit circuit 26, and the polarity as shown in FIG. appears as a (-) output and the diode 27 conducts, acting to cancel the already applied tension current reference 24 and compensation current reference 25.

In general, once the loop car 14 is started, the above correction is relatively easy while it is moving at a constant speed or a constant acceleration/deceleration rate. These corrections were made by compensation, so-called block forcing.

Conventional control has been explained above, but when there is a difference in the flow on the inlet and outlet sides, the current is adjusted by correcting acceleration/deceleration torque, etc., instead of directly adjusting the speed of the loop car 14 according to the difference. There is.

However, in a transient state at startup, it is difficult to accurately correct the changes in acceleration/deceleration rate, the transition from static friction torque to dynamic friction torque, and the torque required for movement. Therefore, conventional control can be used satisfactorily in processing lines that have a margin for tension fluctuations during start-up, but the above fluctuations cannot be tolerated due to constraints such as the strip dimensions, material, and processing temperature. It was necessary to improve the difficult processing lines. In addition, since conventional control does not have a speed control system for directly adjusting the speed, it is necessary to provide a separate speed control system outside the current control system even for speed standards required such as inching. However, unless a switching function with the speed control circuit is added to the speed limiting circuit, the circuit would be complicated.

The purpose of the present invention has been made in view of the above-mentioned drawbacks, and is to improve the followability when starting a loop car,
It is an object of the present invention to provide a tension control device for a steel strip that can reduce tension fluctuations in the steel strip.

Another object of the invention is to provide a strip tension control device whose speed can be adjusted independently.

The present invention will be described below with reference to an embodiment shown in FIG.

Loop car driving electric motor 15, variable voltage power supply 2
1, a current detector 22, and a current control amplifier 23, the configuration of the current control system is the same as that shown in FIG. 1, so a description thereof will be omitted. A speed feedback signal from the speed detector 31 of the loop car 14 is connected to the speed control amplifier 41, and its output is connected to the current control amplifier 23 to form a speed control system.

Next, the following two reference signals are given as speed reference signals to the speed control system described above. First, the difference between the entrance speed standard 28 and the exit speed standard 29 is the first
is given as a speed standard. As a second speed reference, the output of the current control amplifier 42 is applied to the speed control system via the maximum output limiter 43 and the tension control operation contact "X" 44. The second current control amplifier 42 has a tension current reference 2 as a reference signal.
4 and a compensation current reference 25 are connected, and a signal from the current detector 22 is connected as a feedback signal to constitute a second current control system.

Loop car driving electric motor 15, speed detector 31 for the same, variable voltage power supply 21, current control amplifier 2
3. The speed control device composed of the current detector 22 and the speed control amplifier 41 constitutes a speed control system with the first current control system as a minor loop.

Next, the operation of the present invention will be explained according to the operating order of the loop car 14.

First, during individual inching or threading when there is no strip, the tension control contact "X" 44 is opened and a inching speed reference (not shown) is provided in place of the first speed reference. The loop car 14 is operated according to the speed control system response according to a given speed criterion.

Next, after threading is completed, the tension control contact "X" 44 is closed in order to apply tension to the steel strip while keeping the first speed reference at zero. The current reference for the second current control system is provided by tension current reference 24. Compensation current reference 25 is loop car 1
This is to give the acceleration/deceleration torque and running friction torque when the loop car is running.At the moment, the loop car is stopped, so it is zero. In this state, the loop car 14 is in a stopped state restrained by the steel strip, and tension is applied to the steel strip by a current according to the tension current reference 24. In this state, the incoming and outgoing sections are started at the same time, and if there is no difference in their speed references, the first speed reference remains zero and the loop car 14 remains stopped as before.

Next, a case where the loop amount is increased by making the inlet speed higher than the outlet speed in processing the inlet section will be described. In order to increase the inlet speed which has been in synchronization with the outlet speed until now, the inlet speed standard 28
is increased at a certain rate. As a result, the first speed reference, which has been zero until now, is increased at a constant acceleration rate.

In this case, when starting the loop car 14, acceleration torque and friction torque are required for starting, and especially at the time of starting, the friction torque changes from static friction to dynamic friction, so the starting torque changes in a complicated manner. However, since these fluctuations in starting torque are configured by the speed control system, they are automatically compensated for and the loop car electric motor 15 starts immediately.

On the other hand, the current reference given to the current control amplifier 42 is the tension current reference 2, which has already been given.
4, but a compensation current reference 25 is further added at the same time as the loop car 14 is activated. This compensation current reference 25
The contents are the torque required for acceleration and running of the loop car 14 converted into a current standard. As described above, the starting torque required when the loop car 14 starts up varies greatly immediately after starting up, so it is difficult to accurately provide it as the compensation current reference 25. Conventionally, this compensation reference value has been given as the acceleration torque and running friction torque in a state where steady acceleration has entered, that is, at a constant acceleration rate, without considering the value during the above-mentioned transition period.

The response of the second current control system is the current control amplifier 4
By adjusting the proportional gain or integral gain of 2, the response can be adjusted independently from the response of the speed control system which becomes a minor loop. In the present invention, the response of the second current control system is set to be slightly slower than the response of the speed control system. Therefore, immediately after starting the loop car 14, while the torque necessary for starting the loop car 14 is being supplied from the speed control system described above, the output of the current control amplifier 42 is almost unchanged due to the difference in response described above. It does not change. As the loop car 14 begins to start, the output of the current control amplifier 42 begins to vary in response to its actual current relative to the applied current reference, and eventually the actual current of the motor 15 changes from the current required by the speed control system. The current required by the second current control system is equal to the current reference value given as the sum of the tension current reference 21 and the compensation current reference 25.

In the above explanation, the setting of the compensation current standard was simply described in the case of a constant acceleration/deceleration rate, but the running friction torque is also determined depending on the loop car running direction, running speed, length of the strip steel in the loop car 14, and weight. etc., and it is necessary to compensate for these values, but the extent to which compensation is determined is determined by the performance of the system, and what can be achieved based on the technical idea of the present invention is it is obvious.

As described above, according to the strip steel tension control device of the present invention, the starting torque, which has a large variable factor immediately after starting the loop car, is supplied by the speed control system, and during steady acceleration, when the required torque can be grasped relatively accurately, the starting torque is supplied by the speed control system. Since the required torque is supplied by the current set by the compensation current reference, the tension in the steel strip can be maintained at the set value even during acceleration. That is,
This has the effect of improving speed followability with respect to loop car acceleration/deceleration, and reducing the influence of fluctuations in acceleration/deceleration torque on tension.

Further, according to the present invention, since a speed control system is provided as in the prior art, the speed required during independent operation or threading can be easily obtained without providing a special switching circuit.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram of a line showing the relationship between the loop storage equipment and the equipment before and after it, Fig. 2 is a block diagram showing tension control of a conventional loop storage equipment, and Fig. 3 is a block diagram showing an embodiment of the present invention. It is a diagram. DESCRIPTION OF SYMBOLS 11... Inlet bridle, 12... Outlet bridle, 13... Steel strip, 14... Loop car, 15... Loop car drive motor, 22... Current detection circuit, 23...
Current control amplifier, 24...Tension current reference, 25...Compensation current reference, 28...Inlet speed reference, 29...Output speed reference, 41...Speed control amplifier, 42...Current control amplifier, 43...Maximum output limiter, 44 ...Tension control contact.

Claims (1)

[Claims] 1. A speed control system for maintaining the speed of an electric motor that drives a looper at a predetermined value in a loop storage facility for a continuous steel strip processing line that is installed between two sections operated at independent speeds and stores strip steel; The speed control system is made into a minor loop and includes a current control system for maintaining the current of the motor at a predetermined value, and a signal corresponding to the speed difference between the two sections is added to the reference of the speed control system, and the current A tension control device for a steel strip, characterized in that a current reference signal for maintaining the tension of the steel strip at a predetermined value is added to a reference of a control system.