KR100530333B1 - Speed control device of rolling mill for improvement coiling shape and preventive necking - Google Patents

Abstract

The present invention relates to a speed control method of a finishing mill for preventing the hot-rolling shape and the width necking, the strip is passed through the final stand of the finishing mill and proceeds to the first acceleration pattern, and then reaches the thermometer in front of the winder When it stops the acceleration of the finishing mill speed and at the same time maintains the constant speed, and if the tension is formed while the strip is wound on the winding machine in the section maintained at the constant speed, the rolling speed of the finishing mill is accelerated secondly after 0.5 seconds from that point At the start of the second acceleration, only 60% of the finishing accelerator instruction acceleration is accelerated so as to provide a stable tension between the finishing mill and the winder.

According to the present invention, it is possible to prevent the width necking caused by the exaggerated tension caused by the tension variation due to the speed difference between the finishing mill and the winding machine at the time of winding of the strip end, thereby preventing the width defect, and also stably from the beginning of the winding. By providing tension, the winding shape is improved, and the error rate of the product is improved.

Description

SPEED CONTROL DEVICE OF ROLLING MILL FOR IMPROVEMENT COILING SHAPE AND PREVENTIVE NECKING}

The present invention, by changing the speed pattern of the finishing mill to improve the coilability at the time of winding the strip end portion in the winder, to prevent malfunction due to unwinding, to prevent the shortage of width due to exaggeration, poor winding quality due to tension sudden change, etc. The present invention relates to a speed control method of a finishing mill for preventing hot-rolling shape and width necking.

In general, the finishing process of the hot rolling process, finishing rolling and winding process, is a very important work process that has to satisfy two conditions of smooth winding of the strip and securing product quality.

To this end, the hot rolling mill controls this by controlling the speed of the finishing mill and controlling the speed and tension of the winding machine.

That is, as shown in Figure 1, the speed control of the finishing mill 100 is made for the purpose of maintaining a constant temperature to meet the productivity part and metallurgical factors, using a method called acceleration for productivity and constant temperature control For this purpose, acceleration and spray control between stands are combined.

The speed control of the filament mill 100 is generally divided into four types. First, the button is maintained at an initial speed while the button operation is continued by the speed holding button operation of the driver, and in the fixed acceleration section as shown in FIG. 2. The fixed acceleration amount is controlled in a predetermined pattern. That is, the first and second acceleration amounts 500 and 501 set in the finishing mill PLC 108 are used for acceleration control in each execution section.

Third, as shown in FIG. 3, the thermometer 101 performance at the exit of the finishing mill 100 is calculated as a temperature performance deviation 200 from the performance compared to the reference temperature, and divided into four sections for each dimension and steel grade in the finishing mill PLC 108. Acceleration amount is set by dividing the acceleration amount into constant velocity 201, low speed 202, and high acceleration 203 according to the temperature performance deviation 200, and within the first and second acceleration amounts 500 and 501, Acceleration control is applied by separately applying the acceleration amount of the section.

Fourth, the third acceleration control pattern is maintained, but despite the speed control, if the deviation occurs in the finishing mill exit thermometer 101 with respect to the reference temperature, the pressure of the spray between the stands of the finishing mill 100 is added or decreased in parallel. Method to control temperature and speed.

In the conventional hot rolling mill, since the third method is mainly used, the first and second acceleration sections have two first and second acceleration sections, and thus, the speed change has a lot of forms depending on the thermometer 101 at the exit of the finishing mill 100 in each acceleration section. have.

In addition, the structure of the winder 104 is to increase the winding capacity of the mandrel winding the strip 102 directly, the pinch roll for generating a proper tension at the end, the end of the strip 102, the end of the strip 102 For example, a unit roll for pressing the strip 102 to the mandrel.

The control between the finishing mill 100 and the winding machine 104 can be largely divided into speed control and tension control, and in the case of the front end of the strip 102, the tension between the finishing mill 100 and the winding machine 104 is still present. Since it is not in the hanging state, it corresponds to the part for speed control, and when the tip portion is wound around a certain amount, tension is generated, and then it is switched to tension control.

The tension used as a reference for the control is to use the value converted from the motor current value of the mandrel to the tension, when the converted tension current value is less than the initial reference current value, the speed control of the winding machine 104 is the finishing mill 100 The lead rate is added to improve the winding property to the speed so as to follow the speed of the finishing mill 100.

Here, the relationship between the speed of the finishing mill 100 and the speed of the winding machine 104 is as follows.

Τ: winder speed

ν: finishing mill final stand speed

β: finishing mill final stand advance rate

κ: lead rate

T = νx (1 + β) x (1 + κ)

At this point, the mandrel is rotating faster than the strip 102 speed just before the mandrel motor becomes a predetermined current value at the time when a predetermined tension is generated at the distal end and the tension control is switched, and the strip 102 is rotated 5 to 7 times on the mandrel. Even if a current value is generated due to the inertia of the material, the tension is applied to the tip end more than the proper tension due to the inertia. A necking phenomenon occurs in which the width of the strip 102 is locally reduced between 100 and the winder 104.

Such a width necking phenomenon causes a considerable weight width defect, and even if a defect does not occur, it causes a width deviation in the strip 102, resulting in a dissatisfaction of the demand.

In addition, the speed change of the finishing mill (100) at this point is shown as a tension change between the finishing mill (100) and the winding machine (104), and this tension change is developed into a poor winding state of the inner coil of the winding coil and is severe. This leads to a situation where the coil cannot be wound due to the severe tension change at the tip.

The present invention has been made to solve the above problems, by setting the speed control of the finishing mill, which is the target of the winding machine control, according to the winding situation of the winding machine, the width necking phenomenon and the winding portion of the inner winding shape due to inadequate tension It is an object of the present invention to provide a method of controlling the speed of a rolling mill to prevent hot-rolling shape and width necking to prevent a malfunction caused by a winding failure of a strip end of a winding machine.

The above object of the present invention is to proceed to the first acceleration pattern after the strip passes through the final stand of the finishing mill, and then reaches the thermometer in front of the winder to stop the acceleration of the finishing mill speed and maintain the constant velocity at the same time. When the tension is formed while the strip is wound around the winder in the section maintained at the constant velocity, the rolling speed of the finishing mill is accelerated secondly after 0.5 second from the point of time, and 60% of the instruction mark of the finishing mill at the beginning of the second acceleration. It is achieved by providing a speed control method of a finishing mill for preventing hot necking and width necking, characterized in that it is controlled to provide a stable tension between the finishing mill and the winding machine by accelerating the bay.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings.

The present invention, as shown in Figure 1, the finishing mill PLC 108 for controlling the speed of the finishing mill, the winding machine front thermometer 103 for generating a constant velocity start signal, tracking the position of the end of the strip to calculate the constant velocity start signal and It consists of a winding machine PLC 106 which generates a constant velocity section end signal by detecting tension generation between the finishing mill 100 and the winding machine 104.

The winding machine PLC 106 transfers the signal to the finishing mill PLC 108 when the position of the front end of the strip 102 currently in progress recognizes the temperature detection signal of the winder front thermometer 103. Will be sent to.

If the thermometer 103 generates an abnormal signal due to water vapor, a problem arises in speed control, so that the calculated position of the front end of the strip 102 calculated by the winding machine PLC 106 is used as a backup means.

That is, in the winding machine PLC 106, the position of the tip of the strip 102 is accumulated and tracked from the moment when the strip 102 exits the final stand of the finishing mill 100, and the calculated value is within 10 m in front of the thermometer 103. If it comes, it will generate a signal.

In the speed control of the finishing mill 100, the control signal is constructed by using the thermometer detection signal and the approach signal of the front end of the winding machine PLC 106 as the condition.

The conventional rolling mill PLC 108, which has conventionally performed the first acceleration, stops the acceleration when the two signals are received and performs the speed control at the constant speed.

In this constant velocity section, when the winding of the tip of the strip 102 starts and the tension of the winder 104 occurs, the secondary acceleration is performed.

Secondary acceleration is likely to cause secondary failure due to too sudden acceleration, so in order to eliminate this risk factor, the finishing mill speed controller outputs only 60% of the set acceleration amount for 2 seconds after the winding machine tension is generated. This is preferable.

Two seconds after the tension is generated in the winder 104 is controlled by the existing acceleration amount.

Since the tension fluctuation is eliminated by the constant velocity section control by this invention, a stable winding is made.

Therefore, it is possible to prevent the width necking, the unwinding, the winding shape defect, and the like generated between the finishing mill 100 and the winding machine 104.

The acceleration amount applied in the above process is usually applied by a predetermined table value and the values are shown in Table 1 below.

The strip used here is plain steel with a thickness of 2.0 mm and the unit is mpm / sec.

Thickness / acceleration 1 acceleration 2 acceleration LOW 1 HIGH 1 LOW 2 HIGH 2 1.6mm 2 3 4 6 1.9mm 2 3 4 10 2.1mm 2 3 5 10 2.3mm 3 4 6 12 3.2mm 3 4 6 12 4.0mm 4 5 6 10 5.0mm 3 4 6 8 6.0mm 2 4 5 8 8.0mm 2 4 5 8 13.0mm 2 4 5 8

Example 1

Referring to FIG. 4, an embodiment according to the present invention will be described. When the strip 102 enters the sixth stand, the first acceleration 601 is performed.

At this time, the rolling speed of the sixth stand is 620m / min and the first acceleration rate is 2m / min per second in the case of low speed, 3m / min per second in the case of high acceleration.

Usually, the primary acceleration is 3m / min per second because the steel grade thickness has no low speed section and only high acceleration section.

The leading edge of the strip becomes faster than the rolling speed due to the advancement rate of the 6th stand. The value is about 649m / min at the time of exiting the 6th stand, and the acceleration amount is 3m / min (601) per second. If the distance 110m to the intake thermometer is advanced, the take-up PLC 106 generates a 10m forward point passing signal in front of the thermometer 103 at the front end of the strip, and then, when the strip 102 reaches the thermometer 103, the winder The PLC 106 generates a thermometer arrival signal.

When these two signals are generated, the speed control of the finishing mill 100 is switched to the constant velocity 604, and the strip speed at the time of switching to the constant velocity is 679 m / min, and the time to reach it is 10.14 seconds.

The transition to the constant speed was 20m for the first winding machine and 29.5m for the second winding machine.

Proceeding this distance at a constant velocity 604, the winder speed control will appear in two different forms.

One of them is that the amount of acceleration torque for accelerating is not necessary, and since there is no change in rolling speed of the sixth stand, the speed following control of the motor required in case of a change in the speed of the finishing mill is not necessary.

Therefore, the motor of the winder can be sufficiently prepared up to the desired speed value up to the start of the winding.

Therefore, there is no controllable speed change at the time when the strip tip is wound, and there is no tension change between the finishing mill and the winder occurring at the difference between the finishing mill and the winder speed.

The duration of the constant velocity section is about 2.55 seconds for winder 1 and 4.31 seconds for winder 2 when it is assumed that a reference tension occurs when the strip is wound 5 to 7 turns in the winder. The difference in arrival time from the case of continued operation was within 0.05 seconds.

While maintaining the constant velocity section, it was found that the position tracking and motor control of the strip end of the take-up PLC were made stable, thereby minimizing the tension variation of the tip.

By minimizing the tension fluctuation, the lead rate of about 4%, which has been conventionally applied, can be reduced to 2% or less, thus eliminating the phenomenon that the width is reduced by the exaggerated force generated between the finishing mill and the winder.

Once tension was formed between the finishing mill and the winding machine, secondary acceleration (606, 608) was performed for a time at which the tension could be stabilized, that is, a time delay 605 of 0.5 seconds.

At the beginning of the second acceleration, the strip winding shape may be deteriorated by the tension change due to the sudden speed change, so only 60% (606) of the applied acceleration rate is applied for one to two seconds from the start of the second acceleration. This is preferred.

After that, control was performed according to the existing acceleration pattern with the existing acceleration amount.

The control time increased by applying the new pattern to the existing control pattern is about 1.5 seconds, and this increase can be offset by the upward adjustment of the first acceleration amount and the second acceleration amount. It is obvious.

As described in detail above, according to the present invention prevents the width necking caused by the exaggerated tension caused by the tension fluctuation caused by the speed deviation between the finishing mill and the winder at the time of winding the strip end to prevent the width defect In addition, the winding shape is improved by providing a stable tension from the beginning of the winding has the advantage that the error rate of the product is improved.

1 is a schematic installation state of the finishing mill and the winding machine of a typical hot rolling equipment,

2 is a graph showing an acceleration pattern of a rolling speed of a conventional finishing mill;

3 is a schematic view showing an acceleration section setting method for determining an acceleration amount of a finishing mill;

Figure 4 is a graph showing the acceleration pattern of the finishing mill changed by the present invention.

Explanation of symbols on main parts of drawing

100: finishing mill 102: strip

104: winder 106: winder PLC

108: finishing mill PLC

Claims (3)

After the strip passes through the final stand of the finishing mill, it proceeds to the first acceleration pattern, After reaching the thermometer in front of the winder, it stops the acceleration of the finishing mill speed and maintains the constant velocity. When the tension is formed while the strip is wound around the winder in the section maintained at the constant velocity, the rolling speed of the finishing mill is accelerated secondly after 0.5 second from that point, At the start of the second acceleration, the speed control method of the hot rolling mill for preventing the hot-rolling shape and the width necking is characterized by controlling to provide a stable tension between the finishing mill and the winder by accelerating only 60% of the instructional acceleration of the finishing mill. . The hot rolled winding shape and width necking according to claim 1, wherein the section maintained at the constant velocity is controlled to receive the position signal of the front end of the strip of the thermometer and the winding machine PLC until a point at which tension is stably formed in the winding machine. Speed control method of finishing mill for prevention. According to claim 1, wherein the secondary acceleration start time is controlled for 1 second from the time of forming a stable tension to the winder to improve the responsiveness of the hot-rolled winding shape and characterized in that the finishing mill for preventing the width necking Speed control method.