JPS6021117A - Driving device for descaling line - Google Patents

Abstract

PURPOSE:To prevent tripping of driving motors with fast control response by constituting a titled device in which the currents of the driving motors for the bridle rolls on an inlet side is decreased when the max. current value of the driving motors of the bridle rolls on the outlet side exceeds a set value. CONSTITUTION:The currents of driving motors 24-26 for bridle rolls 16 on an outlet side provided with a current control device 64 are detected with current detectors 44 and the max. value of the currents is detected by a diode 46 and is outputted to a control device 48 in a descaling line provided with bridle rolls 14, 16 on the inlet and outlet sides and a scale breaker 10. A signal is outputted to a current control device 40 of the driving motors 32, 34 for the bridle rolls 14 on the inlet side to decrease the driving current set with a potentiometer 42 when the max. current value inputted to said circuit is compared with a set value and when said value exceeds the set value. The tension on a steel strip S is decreased to prevent easily and surely the tripping of the motors by the above- mentioned method when the driving motors 24-28 for the rolls 16 on the outlet side slip.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a drive device for a descaling line that includes a scale breaker and pre-dol rolls before and after the scale breaker.

A cold rolling mill further rolls the steel strip rolled in a hot rolling mill into a thin plate of a predetermined thickness, but since there is scale attached to the surface of the steel rolled in a hot rolling mill, before rolling it in a cold rolling mill. By removing this, the workability of cold rolling is improved, and the appearance, paintability, and workability of the cold rolled sheet are ensured. Figure 1 shows this scale removal equipment, where 10 is a scale breaker that mechanically removes scale, and 20 is an acid (20) that chemically removes scale.
Hydrochloric acid) tank. 12 is a loop car, which is a device (not shown) for unwinding the copper strip wound into a coil in a hot rolling mill;
The steel strip S is received from the steel strip S, the tension is adjusted, and the steel strip S is sent to the priddle roll 14 on the inlet side of the scale breaker. In the scale breaker 1o, the steel strip S is passed through a plurality of rolls while being bent as shown in the figure, and relatively large scales are peeled off and removed by the bending. Reference numeral 16 denotes a priddle roll on the exit side of the scale breaker, which transports the steel strip coarsely descaled by the scale breaker to an acid tank 2o, where fine scale is removed. 22 is acid chloride (the rule of pridle roll).

Prydle roll 14 on the scale breaker inlet and outlet side
and 16 in this example consist of 20 and 30 rolls, respectively, and each roll is individually driven by a motor 32, 34.24, 26.28 as shown in FIG. 2fa). The loop car 12 is also driven by the motor 30, and the exit prydle roll 16 determines the transport speed of the steel strip S, while the loop car 12 and the input prydle roll 14 pull the steel strip S to impart tension to it. Exit side priddle roll I
6 overcomes this tension and drives the steel strip S to feed it into the acid tank 20 at a predetermined speed. However, in the scale breaker 10, dust is generated due to descaling, and water is sprayed to prevent this scattering, so the steel strip The friction coefficient of S is reduced, and the exit side pry roll 16 is likely to slip.

If one of the exit pry rolls slips, the drive motors of the remaining two rolls will carry the full load and may become overloaded. The second [Hb) shows the current change of each motor when a slip occurs in the center roll, and when the center roll slips at time to, the current of the drive motor 2G decreases rapidly, and instead of the left and right rolls. The current in the drive motors 24 and 28 increases rapidly, causing the overload relay to disturb and shut off the power supply.The load on the output side priddle roll 16 is caused by the scale breaker 10 in addition to the copper strip tension mentioned above. There is also the required power. In Figure 3, the horizontal axis shows the scale breaker inlet tension, the vertical axis shows the required power of the exit priddle roll 16, and the thickness and rolling reduction of the steel strip to be scaled are taken as parameters. A graph illustrating the required power.
And as the plate thickness increases, the curves become C1, C2,...
The required power increases in this order. Slip and motor trigger knobs are more likely to occur when the power is increased.

Possible trip countermeasures include: ■ Adjusting the motor capacity knob, ■ Dulling the exit side priddle roll, and ■ Controlling the scale breaker. However, although (2) and (2) are effective as trip countermeasures, the equipment costs are high, and (3) in particular has the problem that the 6fi band surface is scratched by the dull (roughened) roll. In addition, the response in case (3) is slow, so it is not very effective as a trip countermeasure, and requires the installation of an electric valve.

The present invention is intended to provide quick control response and low equipment costs.The tension of the inlet prydle roll is adjusted according to the load on the outlet prydle roll, thereby preventing the tripping of the outlet prydle roll drive motor. This is what we are trying to prevent.

The present invention is equipped with a scale breaker and its inlet and outlet prydle rolls. In a descaling line drive device that is equipped with a control device that controls the tension of The present invention is characterized in that it is provided with a circuit that outputs a signal for reducing the current of the input side priddle roll drive motor to the control device of the input side priddle roll drive motor when a set value is exceeded. Explain.

FIG. 4 shows an embodiment of the present invention, in which the same parts as in FIGS. 1 and 2 are given the same reference numerals. 36 is a current control circuit for the drive motor 30 of the loop car 12, which controls the motor current and the tension of the steel strip S to a value set by a potentiometer 38.

40 is a drive motor 32.3 of the entry side priddle roll 14
A current control circuit for 4 controls the motor current and thus the tension of the steel strip S to the value set by the potentiometer 42.

Drive motor 24, 26.2 of the exit side priddle roll 16
The current of 8 is taken out by the current detector 44, and the current of
Accordingly, the largest one is taken into the control circuit 48. Details of this part are shown in FIG. In other words, control time 1? J48 receives the output of the isolation amplifier 50 that outputs the maximum value, and produces an output when it exceeds the value set by the set value 52 (comprising a comparator 54.
The input circuit and the feedback circuit are equipped with capacitors to perform PID control, and the feedback circuit is equipped with anti-parallel diodes to control the output to a predetermined value.

The output of the control circuit 48 is applied to a subtracter 56,
4. ．． When the maximum current of 26.28 exceeds the setting value of the setting device 52, the current setting value of the drive motor of the entry side priddle roll 14 by the potentiometer 42 is decreased. Therefore, when a slip occurs and an overcurrent flows through the drive motor of a roll that does not cause slip, the tension of the entry side priddle roll is immediately reduced, the overcurrent is prevented, and motor trip is avoided.

The subtracter 56 is composed of an adder as shown in FIG. The current reference value set by the potentiometer 42 is output. When the comparator 54 produces an output (the output terminal becomes low level), the diode 58 is turned on, and the input voltage of the adder 56 decreases, causing the output voltage to decrease. The degree is set by the potentiometer 60. Reference numeral 62 in FIG. 7 is a power supply for the motor 24°26.28, which includes a cyrisk and its gate control circuit.

FIG. 5 is a graph showing the required power of the exit side prydle roll 1 (3Br) 16 against the tension of the input side prydle roll (2Br) 14 using plate thickness and rolling reduction as parameters, and curves CI, C2, C3° C4 is a case where the plate thickness and/or reduction increase in this order. If the tension of 2Br is reduced, the required power of 3Br is reduced and motor trips can be avoided.

In addition, 64 in FIG. 4 is a speed control circuit for the drive motor 24, 26, 28 of the exit side bridle roller, and the setting device 66
The speed of the steel strip S is controlled to the value set by . 68 is an adder, and a detector 70 detects the hanging state (catenary) of the steel strip S in the acid tank 20 along with the output of the setting device 66.
is input, and produces an output that corrects the speed of the exit side priddle roll so that the suspended state of the steel strip S is maintained at a predetermined value. FIG. 6 shows a specific example of a circuit for taking out the motor current, which includes a resistor 72 that receives the motor current I and produces a voltage drop proportional to it, a potentiometer that takes out part of the voltage drop, and a diode 76.

As explained above, in the present invention, when the priddle roll on the outlet side of the scale breaker slips and the motor current on the healthy side becomes excessive, motor trip is prevented by reducing the tension of the inlet side priddle roll. , it is possible to perform coordinated control, and since only the addition of a relatively simple control circuit is required, an increase in equipment costs can be avoided.

[Brief Description of the Drawings] Figures 1 to 3 are explanatory diagrams of descaling lines and graphs showing characteristic examples; Figure 4 is an explanatory diagram showing examples of the present invention;
FIG. 5 is a graph for explaining its characteristics, and FIGS. 6 and 7 are circuit diagrams showing details of a part of FIG. 4. In the drawing, 10 is a scale breaker, 14 is an inlet priddle roll, 32, 34 is its drive motor, 40 is its control device, 16 is an outlet priddle roll, 24, 26 .
28 is its drive motor, 64 is its control installation, 46.5
0 is a maximum value detection circuit, and 52.54 is a circuit that outputs a current reduction signal. Applicant Nippon Steel Corporation Representative Patent Attorney Minoru Aoyagi

Claims (1)

[Claims] It is equipped with a scale breaker and its inlet and outlet prydle rolls. In a descaling line drive device that is equipped with a control device that sets the tension of the steel strip to a predetermined value, there is a circuit that detects the maximum current of each drive motor of the exit side priddle roll, and a circuit that detects the maximum current of each drive motor of the output side priddle roll. A drive device for a descaling line, comprising a circuit that outputs a signal for reducing the current of the inlet prydle roll drive motor to a control device for the inlet prydle roll drive motor when the current value exceeds a set value.