JPS6043755B2 - speed control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a speed control device for a wire rod rolling facility or the like, which has a drooping characteristic so that the motor speed decreases as the load current of the drive motor increases.

Generally, the arrangement of the machine is such that the exit side of the finishing stand (or NT stand) is equipped with equipment for drawing in material from the finishing stand, such as a foil guide (or finishing pinch roll), and a laying reel (or polling roll) is installed on the exit side of the foil guide. In wire rod rolling equipment equipped with winders such as reels,
A speed control device is provided with a droop characteristic such that when the load current of the wheel guide drive motor increases, the speed of this motor decreases.

Normally, it is said that it is more effective to prevent cobbles from occurring if the wire is pulled in at a speed that is higher than the wheel guide speed that is synchronized with the exit speed of the finishing stand.
Here, the term "cobble" refers to the portion of the wire that is cut off at the front and rear ends. When the wire being rolled leaves the finishing stand, the load current of this foil guide motor decreases, and at the same time the foil guide speed increases in proportion to this current.

As a result, when the foil guide speeds up, it acts to push the wire into the rear laying reel, and the coil ring formed by the wire discharged from the laying reel becomes larger, causing problems in rear coil processing. Become.

In order to eliminate these problems, the present invention has a function to turn off this drooping characteristic function at the same time or just before the wire passes through the finishing stand. It is an object of the present invention to provide a speed control device that can perform normal operation without causing speed changes after removal of a finishing stand when the speed is used as a standard. An embodiment of the present invention will be described below with reference to the drawings.

As shown in FIG. 1, the speed control device with drooping characteristics includes a speed control circuit 10, a minor current control circuit 11, a thyristor power supply device 12, a DC motor 13, a speed feedback tachometer generator 14, and a motor current detector. 15, motor speed memory circuit 16, first switching device 17, second switching device 18,
It is composed of a drooping characteristic variable circuit 19.

10, 11 for normal minor current control speed control circuit
The current detection output of the motor current detector 15 is given to the droop characteristic variable circuit 19, and this output signal is sent to the speed control circuits 10 and 1.
1 to obtain drooping characteristics.

At the same time as the wire is removed from the finishing stand, the normally open contact 17a of the first switching device 17 is closed, the normally closed contact 17b interlocked with 17a is closed, and the speed reference is switched to the memory voltage of the memory circuit 16. However, as soon as the wire passes through the finishing stand, the load current decreases, the droop characteristic signal from the motor speed memory circuit 16 weakens, the motor speed increases, and the coil ring on the exit side of the winder becomes larger as described above. In order to prevent this, a second droop characteristic signal switch 18 is provided, and at the same time or just before the wire passes through the finishing stand, the normally open contact of the first switch is closed, the normally closed contact is opened, and the second 2
By opening the normally closed contact of the switchgear, the speed at which the wire exits the finishing stand can be maintained without increasing the speed of the motor. Figure 2 shows the motor current detection circuit 1 in Figure 1.
The output of the speed control circuit 10, that is, the current reference, is used instead of the current detection in FIG.

Incidentally, although not shown, the decrease in the load current can be detected by a load detector that detects whether there is material or not, or a detector that detects changes in the motor current.

As described above, according to the present invention, in a speed control device equipped with a droop characteristic, the droop characteristic is turned off when the load decreases,
Since the stored speed at that time is used as the speed reference, production efficiency can be improved without causing any trouble to subsequent coil processing, etc.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing one embodiment of the present invention, and FIG. 2 is a circuit diagram showing another embodiment of the present invention. 10... Speed control circuit, 15... Motor current detector, 16... Motor speed memory circuit, 17
, 18...first and second switching devices, 19...
・Droop characteristic variable circuit.

Claims (1)

[Claims] 1. A speed control device for an electric motor equipped with a droop characteristic function, which includes a device for storing the speed of the motor, a circuit for detecting a decrease in motor load, and an output of the storage device based on the output of the detection circuit. A speed control device comprising: a switching device that simultaneously turns off the drooping characteristic function, and prevents speed increase due to load reduction.