JPH0514774B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to a control method for preventing a narrowing of the head width of a hot strip winding machine, and in particular, to a method for controlling the narrowing of the head width of a hot strip winding machine, and particularly to a method for controlling the narrowing of the head width of a strip located before the pinch roll. This invention relates to new improvements for preventing netting, netting, and the like.

b. Prior Art In general, the strip tip winding torque in a continuous hot band steel winding machine is given by inertial energy due to the lead speed of the mandrel relative to the strip speed.

Therefore, the greater the mandrel lead ratio, the greater the winding torque, and the better the head winding properties of the strip.

However, as this winding torque increases, the tension impact generated between the final finishing mill stand and the mandrel during winding also increases, increasing the width shrinkage phenomenon of the strip.

This phenomenon is called netting, and it becomes an obstacle to ensuring width accuracy in hot rolling equipment.

In addition, in winding machines that handle a wide range of products, from thick to thin, and from ordinary steel to stainless steel, the strength of the mechanical structure is designed to handle products that are thick and highly rigid. The inertia (GD ² ) of the mechanical system of the mandrel is large, and the problem of netting has become apparent.

In addition, in recent years, width control has been introduced in hot rolling mills in an effort to improve width accuracy, but the more width accuracy improves, the more this netting problem comes to the fore as a limit to total width accuracy. It's coming.

First of all, it is difficult to predict the location and amount of netting. Secondly, the slope of the width variation is steep, which makes correction difficult with width control (AWC).

On the other hand, the problem of coiler netting can be viewed as a tension impact when the tip of the strip is wound around the mandrel.

Therefore, if the inertia (GD ² ) of the mechanical system of the mandrel is constant, the amount of netting is proportional to the plate thickness, plate width, and mandrel lead ratio.

Further, the required torque for mandrel winding is proportional to the plate thickness, plate width, and rigidity.

For this reason, although the name of the document disclosing the method is not listed here as a conventionally used method for controlling the head width reduction prevention of the hot strip winding machine,
One example is a method in which the finished product is divided into plate thickness, plate width, and steel type, and the mandrel speed lead rate for each category is set to the optimum value using a constant table installed in the arithmetic and control unit. It has been.

c. Problems to be Solved by the Invention Since the conventional method for controlling head width reduction prevention for a hot band steel winding machine was configured as described above, there were various problems as described below.

(1) Since there is an error of several percent in the advance rate of the final rolling mill stand, it is necessary to prevent the mandrel lead from becoming zero due to this error, so a margin for the same error is provided in the mandrel lead. As a result, it was impossible to lower the read rate to the optimal value.

(2) This mandrel performs tension control, and during no-load operation, the speed limiter controls the tension until the set tension current value is reached.
This prevents the rotation from increasing (out of control).

Under such control conditions, when the tip of the strip is wound around the mandrel, the mandrel rotation slightly decreases during the initial tensioning stage before winding, causing the strip to go out of the range of the speed limiter and reach the set tension current value. , the tension current rises.

For this reason, during most of the process of winding the strip, the inertial force of the mandrel and the tension output of the mandrel overlap, making the tension impact even greater.

Therefore, with the above-mentioned control method, it is not possible to avoid netting due to tension impact between the mandrel and the final finishing mill stand when the strip tip is wound.

In other words, netting occurs not only at the tip of the strip, but also over a fairly long distance (approximately 160 m) from the final rolling mill stand to the tip, which has a significant negative impact on the finishing yield of the finished product. was.

The present invention has been made to solve the above-mentioned problems. In particular, the present invention has been made to prevent the netting of the strip between the mandrel and the pinch roll, and to prevent the netting of the strip located before the pinch roll. An object of the present invention is to provide a control method for preventing head width reduction of a strip steel winding machine.

d. Means for Solving the Problems The method for controlling the head width reduction prevention of a hot strip winding machine according to the present invention includes a mandrel for winding a strip from a final finishing rolling stand of a finishing rolling mill, and a and the final finishing rolling stand, and includes a pinch roll for holding back tension, and a pinch roll control section for controlling the pinch roll, The moment when the tip of the strip is bitten by the pinch roll is detected by a strip tip detector installed in the final finishing mill stand, and the speed trap of the strip at the time of this detection is used to detect the moment when the tip of the strip is bitten by the pinch roll. The arithmetic control unit of the control unit performs a first step of tracking the position of the tip of the strip, and as a result of the tracking of the tip of the strip, the tip of the strip reaches the mandrel and enters the first roll operation, and then the final finishing rolling machine is started. Predict the time from the moment tension is started between the stand and mandrel until the winding is completed.
Meanwhile, the strip speed V against the pinch roll
- By giving a speed reference of α, the tip of the strip reaches the mandrel and after the first roll, the pinch roll is decelerated to provide back tension, which becomes the second step, which occurs at a position before the pinch roll. This is a method for preventing the strip width reduction phenomenon.

e Effect: In the method of preventing the head width of a hot band steel winding machine according to the present invention, the tension impact generated at the moment when the tip of the strip is wound around the mandrel is applied to the pinch roll as a back tension, thereby reducing the pinch roll. Even if excessive tension is applied to the strip in a short range between the roll and the mandrel and netting occurs, it can be limited to the short range held by the pinch roll from the tip of the strip, and the part before the pinch roll is Netting on the strip can be prevented.

In addition, since the strip is cooled between the pinch rolls and the final finishing mill stand by controlling the winding temperature, the temperature of the strip that has reached the mandrel has already decreased by several hundred degrees, so the plasticity coefficient of the strip has decreased. As a result, the amount of netting itself between the mandrel and the pinch roll becomes negligible.

f Example Hereinafter, a width reduction prevention control method for a hot band steel winder according to the present invention will be described in detail with reference to the drawings.

1 to 5 are for showing the control method according to the present invention, and FIG. 1 is an overall configuration diagram, and FIG.
3 is a time chart, FIG. 4 is a detailed block diagram of the main part of FIG. 1, and FIG. 5 is a characteristic diagram showing the winding of the strip.

In FIG. 1, the reference numeral 1 indicates a hot winding machine, and this hot winding machine 1 includes a hot run table 5 consisting of a mandrel 2, a pinch roll 3, a number of rollers 4, and a final finishing machine. It consists of a rolling mill stand 6.

The pinch roll 3 is a hot run table 5.
A strip tip detection device consisting of an accelerometer is installed on the upper surface of the pinch roll 3 to detect the passing of the tip of the strip 7 fed on the hot run table 5. A pinch roll motor 9 consisting of a DC motor for driving the pinch roll 3 is provided on the shaft of the pinch roll 3 .

Furthermore, on the shaft of the pinch roll motor 9,
A first pulse generator 10 (hereinafter referred to as a first PLG) for detecting the rotation of this pinch roll motor 9
) and a pilot generator 11 (hereinafter referred to as PG) are coaxially connected by a mechanical shaft (not shown).

The roll 12 of the final finishing mill stand 6 is provided with a second pulse generator 13 (hereinafter referred to as second PLG) as a strip speed detector for detecting the speed of the strip 7.

Next, what is indicated by the reference numeral 14 is a pinch roll control section, and this pinch roll control section 14
is the strip tip detector 8, the first PLG 10
and an arithmetic control unit 15 into which the output signal from the second PLG 13 is input, the PG 11 and the arithmetic control unit 15
Speed control loop 1 into which the output signal from
6. Current control loop 17 into which the output signal of the speed control loop 16 is input; the current control loop 1;
7, a gate pulse generator 19 to which the output signal of the voltage control loop 18 is input, and a thyristor 20 to which the output signal of the gate pulse generator 19 is input. has been done.

Therefore, the circumferential speed of the final rolling mill stand 6 detected by the second PLG 13 is determined by the calculation control unit 1.
5, the strip speed is calculated by the calculation control section 15, and is given as a speed reference to a pinch roll speed control loop 21 consisting of a speed control loop 16, a current control loop 17, and a voltage control loop 18.

Further, each of the control loops 16, 17 and 18 is
Velocity feedback trap, current feedback trap and voltage feedback trap (V ₀ ) from PG11, respectively.
The deviation between the reference and feedback is calculated and controlled.

In more detail, the pinch roll control section described above is as follows:
It is constructed as shown in FIG. 4, and its general operation will be explained with reference to the characteristic diagram of FIG. 5.

First, the tip of the strip 7 is connected to the mandrel 2.
A case will be described in which the speed of the pinch roll motor 9 is reduced after the first roll and the back tension is obtained. The speed control of the pinch roll 3 can be controlled by the electrical system depending on the operating status of the mechanical system, and in order to obtain the above-mentioned back tension, the arithmetic control section 15 controls the speed of (strip speed - α). The speed reference output signal is sent to the speed control loop 16.
, the rotation speed of the pinch roll motor 9 is reduced, and the pinch roll 3 is changed to (strip speed - α).
The speed shall be .

The rotation speed N of this pinch roll motor 9 is N=
Since it is given by K ₃ ·V/Φ, in order to control this rotational speed N, it is sufficient to lower the applied voltage V. Therefore, when voltage drop control is performed in the voltage control loop 18 as speed control, the pinch roll motor 9
Since the applied voltage is reduced by ΔV via the mechanical strip while maintaining the strip speed, it operates as a generator and rapidly decelerates.

Therefore, the number of rotations of the pinch roll 3, that is, the circumferential speed of the strip 7, is the same as that of the strip 7 until the tip of the strip 7 passes through the pinch roll 3, is wound on the mandrel 2, and the first roll is wound. Back tension is obtained by being slower than the velocity.

This strip 7 is the final rolling mill stand 6
The speed when passing through varies depending on the thickness of the plate, but
As shown in Figure 5, it is usually 10 to 15 m/sec,
This can be achieved by making the circumferential speed of the pinch roll 3 slightly slower than this speed. The time required for this slowing down varies depending on the speed of the strip 7, but 0.5 to 1.5 seconds is usually sufficient.

When the tip of the strip 7 begins to be wound around this mandrel 2, there is no need to apply tension between the pinch roll 3 and the mandrel 2 until the tail end of the strip 7 passes the final finishing mill stand 6, and the pinch roll 3 may be approximately the same speed as the strip 7. This speed control is detected by the PG 11, fed back and compared with a speed reference, and the comparison value is applied to the current control loop 17 and compared with the current reference value. The comparison value, which is the output signal from this current control loop 17, is the output signal from the voltage control loop 18.
By comparing the deviation with a voltage reference and applying the deviation to the pinch roll motor 9 via the gate pulse generator 19 and the thyristor 20, the pinch roll motor 9 is controlled to speed up by the applied voltage trap. Control takes place.

The width reduction prevention control method for a hot band steel winder according to the present invention is configured as described above, and its operation will be explained below.

First, the tip of the strip 7 sent out from the final finishing mill stand 6 is conveyed on the hot run table 5, passes through the pinch rolls 3, and tries to be wound around the mandrel 2, but in the above-mentioned state,
The moment when the tip of the strip 7 is caught in the pinch roll 3 is detected by the strip tip detector 8, and from this timing, using the strip speed trap detected by the first PLG 10, the arithmetic control section 15 , the position of the tip of the strip 7 is tracked.

By the above-mentioned strip tip tracking, the tip of the strip 7 reaches the mandrel 2 and starts the first winding operation, and the period from the moment when tension is started between the final finishing mill stand 6 and the mandrel 2 until the winding is completed is recorded. A speed standard of the amount (strip speed V-α) is given to the pinch roll 3 so that the pinch roll 3 can take back tension during the prediction.

The above-mentioned α is a semi-fixed number within the arithmetic control unit 15 and can be arbitrarily varied.

Next, FIGS. 2 and 3 show the calculation control section 1
5 shows the operation timing and control flow of the head width reduction prevention control logic in No. 5.

First, in Fig. 2, the horizontal axis is time, the vertical axis is mandrel speed a, mandrel tension current b,
Pinch roll speed standard c, pinch roll current d,
It shows the state of the mandrel inertia torque e and the tension f applied to the strip when the tip is wound.

Also, in the dashed-dotted lines A, B, C, and D, A indicates the point when the tip of the strip 7 reaches the pinch roll 3, B indicates the point when the tip of the strip 7 reaches the mandrel 2, and C indicates the point when the tip of the strip 7 reaches the mandrel. D indicates the point at which tension begins to be applied after one winding to the mandrel 2, the rotation of the mandrel 2 begins to change from the lead speed to the synchronous speed of the strip 7, and D indicates the point at which the tip of the strip 7 completes winding onto the mandrel 2. .

The mandrel speed is slightly decelerated from timing B when the tip of the strip reaches mandrel 2 until time C when tightening starts, and from time C to time D, it is decelerated from the lead speed to the strip synchronous speed, and then at time D. to complete the winding. on the other hand,
The mandrel tension current b rises due to a slight decrease in speed from time B to time C, and the steady tension is applied to the strip 7 at time C.

Therefore, in the process from point C to point D,
The mandrel inertia torque e and the torque due to the mandrel tension current b overlap, and an excessive tension is applied to the strip 7. Therefore, as seen in the pinch roll speed reference c, the pinch roll speed reference c is decelerated by α from time C to time D, and the pinch roll 3 is given back tension.

Furthermore, the head width reduction prevention control flow will be explained using FIG.

First, it is determined whether the tip of the strip 7 is caught in the pinch roll 3 (first step 22),
A distance counter (not shown) calculates the distance L _t that the tip of the strip 7 has traveled from the time when the strip is bitten, based on the strip speed detected by the first PLG 10.
(second step 23). If the tip of the strip 7 is not caught in the pinch roll 3, the distance counter is reset and the distance _Lt is cleared to zero (third step 24).

Next, the distance L 1 from the pinch roll 3 until the tip of the strip 7 reaches the mandrel ₂ and reaches the first roll is compared with the distance L _t , and it is determined whether L _t ≧L ₁ is established. (4th step 25), and if YES, set K to 1 (5th step 26).
If NO, return to the start.

Next, the distance L 2 from the pinch roll 3 to the tip of the strip 7 until the tip of the strip 7 is completely wrapped around the mandrel ₂ is compared with the distance L _t , and L _t
Determine whether ≧L ₂ holds true (sixth step 27), and if YES, clear K to zero (seventh step).
Step 28). If the answer is NO, the seventh step 28 is skipped and the process goes to the eighth step 29. In this eighth step 29, it is determined whether K=1 is established, and if YES, a predetermined deceleration α is subtracted from the current speed standard of the pinch roll 3, and this speed is used as the standard. Output (ninth step 30). Also, if NO,
Do not proceed to the ninth step 30 and return to the start.

Furthermore, the distances L ₁ and L ₂ (shown in Figure 5) mentioned above are:
It is determined by considering the current response of the pinch roll motor 9, etc., and in particular, regarding the sixth step 27, it is equivalent to detecting and determining the timing when the speed of the mandrel 2 changes from the lead speed to the synchronous speed of the strip 7. The effects of this can be obtained.

g. Effects of the Invention Since the method for controlling head width reduction prevention for a hot band steel winder according to the present invention has the above-described configuration and operation, the following effects can be obtained.

(1) By decelerating the pinch roll at that moment, the pinch roll can be made to have back tension against the excessive tension that occurs at the moment when the tip of the strip wraps around the mandrel. The excessive tension that occurs is applied only to a small strip located between the mandrel and the pinch roll.
It is possible to prevent the strip from getting caught while being conveyed onto the hot run table.

(2) Due to the effect of item 1, it is possible to reliably prevent netting on the hot strip on the hot run table.

(3) Due to the effect of item 1, it is possible to reliably prevent the thickness phenomenon occurring directly under the roll of the final finishing mill stand.

[Brief explanation of the drawing]

1 to 5 are for illustrating the method for controlling the head width reduction prevention of a hot strip winder according to the present invention. FIG. 1 is a block diagram showing the overall configuration, and FIG.
The figure is a time chart showing the head width reduction prevention control timing, FIG. 3 is a flowchart showing the head width reduction prevention control logic operation of the pinch roll control section of FIG. 1, and FIG. FIG. 5 is a block diagram showing the main parts in more detail, and FIG. 5 is a characteristic diagram showing the winding state of the strip. 1 is a hot winder, 2 is a mandrel, 3 is a pinch roll, 5 is a hot run table, 6 is a final finishing mill stand, 7 is a strip, 8 is a strip tip detector, 9 is a pinch roll motor, 10 is a 1st PLG, 11 is PG, 13 is 2nd PLG (strip speed detector), 14 is pinch roll control unit, 1
5 is an arithmetic control section, 16 is a speed control loop, 17 is a current control loop, 18 is a voltage control loop, and 21 is a pinch roll speed control loop.

Claims (1)

[Claims] 1. A mandrel for winding the strip from the final finishing rolling stand of the finishing rolling mill, a pinch roll disposed between the mandrel and the final finishing rolling stand for holding back tension, and the pinch roll. In a hot band steel winding machine comprising a pinch roll control unit for controlling the rolls, the moment when the tip of the strip is bitten by the pinch roll is determined by the tip of the strip provided on the final finishing mill stand. A first step of tracking the position of the tip of the strip by a calculation control unit of the pinch roll control unit using the velocity (V) of the strip at the time of detection; By tracking, the tip of the strip reaches the mandrel and starts the first winding operation, and predicts the period from the moment when the tension begins to be applied between the final finishing mill stand and the mandrel until the winding is completed. strip speed V-α
The tip of the strip reaches the mandrel by giving a speed reference of A control method for preventing head width reduction of a hot strip winding machine, characterized by preventing the width reduction phenomenon.