JPH1058019A - Method for detecting joined position between metallic slabs in continuous hot rolling - Google Patents

Abstract

PROBLEM TO BE SOLVED: To always accurately detect the joined position between slabs rolled with a finish rolling equipment and simply execute it. SOLUTION: At the time of joining the rear end part of a preceding rolled stock to the tip part of the succeeding slab and detecting the position of the joined part between the slabs in continuous hot rolling for continuously rolling the slabs with the finish rolling equipment 6, rolling load in the finish rolling equipment 6 is detected. On the signal of rolling load, linear phase filters 15, 16 are acted such as amplitude frequency characteristic is a high-pass type having a preset cut-off frequency and steepness and phase frequency characteristic is only a simple delay component determined by preset delay factor and the min. values in a preset time section in the output signals of these linear phase filters 15, 16 is detected as the joined point between the rear end part of the preceding rolled stock and the tip part of the succeeding rolled stock.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a joining position detecting method for detecting a joining position of a metal piece, particularly a steel piece, in continuous hot rolling of a metal piece such as a slab.

[0002]

2. Description of the Related Art Conventionally, in a hot rolling line for a slab, a to-be-rolled slab is heated, rough-rolled, and finish-rolled one by one to finish a hot-rolled steel sheet having a desired thickness. However, in such a rolling method, it is inevitable that the line stops due to a biting failure of the rolled material in the finish rolling, and a truncated portion occurs due to a shape defect at the front and rear ends of the rolled material. And the yield was poor.

Therefore, recently, prior to finish rolling, the rear end of the preceding steel slab to be rolled and the front end of the succeeding steel slab are joined and joined, and this is continuously supplied to the finish rolling mill. The continuous hot rolling method in which the rolling is performed is being adopted.

In such a continuous hot rolling method, a continuously rolled steel slab is cut into a coil by cutting a preceding slab and a following slab before a winding device. At the time of winding, it is desirable in the process that the joining portion between the preceding billet and the succeeding billet is included in the rear end of the preceding billet to form an outer winding of the coil. It is necessary to detect the position of and to cut the billet at the tip of the succeeding billet.

[0005] As for such a method of detecting the joining position of the billet in the rolling line, (1) a method of forming at least two or more holes in the longitudinal direction around the joint of the rolled material and tracking the holes (particularly, (See Japanese Patent Publication No. Hei 4-69004), (2) A method of tracking the difference in width by joining the rear end of the preceding material and the front end of the following material with a width difference therebetween. (Refer to JP-A-89136), (3) The pattern of the temperature deviation caused by the joining method is measured and stored by a thermometer after the joining, and the stored pattern and the pattern from the entrance to the finish rolling mill to the coil winding are stored. Conventionally, a method of collating with a temperature deviation pattern measured by at least one or more thermometers installed therebetween has been proposed.

[0006]

SUMMARY OF THE INVENTION
In the method of (1), since a hole is formed in the steel sheet, that part cannot be shipped as a product and will be cut off.
In addition to lowering yield and increasing truncation costs,
There is a problem that a new hole detector is required. Also,
In the method (2), there is a process restriction that steel pieces having different widths must be joined, and
There is a problem that a partial width deviation may be erroneously detected as a joint. Furthermore, in the method of (3), the time resolution of the radiation thermometer is insufficient to detect a sharp temperature peak at the joint while the steel sheet is running. Since it changes variously due to heat conduction into the slab due to the passage of time later, natural cooling, and cooling by cooling water during finish rolling, etc., it is computational cost to collate the temperature pattern taking all these factors into consideration. There is a problem such as increase.

[0007] As a method that does not require detection by a sensor or the like, (4) an error between a joint point estimated by tracking and an actual joint point, and a pinch roll and a coiler mandrel before the shear corresponding to a control error of the cutting device. A method of cutting the downstream side of the junction just by the sum of the distances between the two has been proposed (Japanese Patent Laid-Open No. Hei 7-100506). However, this method has a problem that the joint cannot be satisfied with the above operation request because the joining point is included in the coil inner winding of the following material. Even if the joining point is included in the rear end of the preceding material by the same method, the joining point is set on the safest side, so the joining point actually goes inside the coil several turns from the outside of the coil Are generated, and problems such as an increase in the cost of truncation in the lower process are caused.

As another method for detecting the position of a steel sheet in a rolling line, a load cell is installed in a rolling mill to detect a rolling load, a rolling load signal is supplied to a differential filter, and the output of the differential filter is output. A plate bite detection method is known in which a point at which a value exceeds a preset threshold is detected as a plate bite start point. Here, the differential filter is a high-pass filter used for removing a stationary component (offset component) of the load signal, and is generally an analog circuit combining a capacitor, a resistor, an inductor, and an operational amplifier. It is configured.

[0009] Since this plate bite detection method differentiates the rolling load signal, it may be conceivable to apply this method to continuous hot rolling to detect the position of the joint of the billets. In other words, in continuous hot rolling, the joints of the slabs are higher in temperature than the surrounding parts, and the deformation resistance at the time of reduction is small, so that the rolling load is locally reduced, similar to the case of plate biting. This is because it is considered that the following signal waveform is obtained.

Therefore, the present inventor repeatedly performed an attempt to detect the joining position of the billet in the continuous hot rolling by the above-described plate bite detection method. As a result, in the continuous hot rolling, since the frequency band of the fluctuation component of the rolling load signal at the joining position is wide, if the analog differential filter as described above is used, the fluctuation component is affected by the dispersion of the phase characteristic. It has been found that the position of the joint cannot be reliably detected due to the change in the polarity of the waveform or the peak portion, or the superposition of the convex noise caused by the residual burr at the time of joining.

The present invention has been made in view of the various problems described above. In continuous hot rolling, the joining position of a slab rolled by a finish rolling facility can always be detected with high accuracy, and it can be easily performed. It is an object of the present invention to provide a method for detecting a joint position of a billet that can be implemented.

[0012]

In order to achieve the above-mentioned object, the present invention joins a rear end of a preceding rolled material and a front end of a succeeding rolled material and continuously rolls them in a finishing rolling facility. Upon detecting the position of the joint of the slab in continuous hot rolling, detect the rolling load in the finishing rolling equipment, for the rolling load signal, the cut-off frequency and steepness, the amplitude frequency characteristics of which are set in advance. A high-pass type having a linear phase filter having only a simple delay component whose phase frequency characteristic is determined by a preset delay coefficient is applied, and a preset value in an output signal of the linear phase filter is set. The minimum value in the time section is detected as a joining point between the rear end of the preceding rolled material and the front end of the succeeding rolled material.

It is preferable that the linear phase filter has an amplitude frequency characteristic of a band pass type in that unnecessary high frequency noise is also removed.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows the configuration of an example of a continuous hot rolling facility suitable for carrying out the present invention.
This continuous hot rolling equipment is used to sequentially roll the material to be rolled.
While rough rolling is performed, the leading end and the trailing end of each rolled material are cut by the entry side cutting device 2 and supplied to the joining device 3, where the rear end of the preceding rolled material 4 and the trailing rolled material 5 After joining with the tip, the rolling is finished by a finishing mill 6, and the rolled steel strip is cut by a cutting device 7 and wound into a coil by a winding device 8. Here, the finishing rolling mill 6 is generally composed of, for example, a plurality of stages of about seven stands, and each stand is provided with a force detecting means 10 such as a load cell in order to control a rolling load. I have.

In one embodiment of the present invention, a rolling load signal from a force detecting means 10 of an optional stand of the finishing mill 6, preferably a final stand, is supplied to a waveform analyzing apparatus 11 having a linear phase filter to produce a steel sheet. Detect the joint of the pieces.

Here, a rolling load signal waveform actually measured by the force detecting means 10 is as shown in FIG. 3, for example. In other words, in portions other than the joint, the rolling load becomes substantially constant, and in the vicinity including the joint, the billet overlaps with the slab, so that the rolling load increases more than the set amount, and the temperature in the joint is higher than the surrounding portion. And the rolling resistance is locally reduced because the deformation resistance during rolling is low. Therefore, it is sufficient to detect the minimum point of the load corresponding to the joint position shown in FIG. 3 (time t _X).

Next, the linear phase filter used in the present invention will be described. When the number of stages is N, the transfer function H
(Ω) is

(Equation 1) It is expressed by a rational expression. In the equation (1), ω is a variable representing a frequency, and j is an imaginary unit of j ² = −1.

As is generally known, the phase component (declination of the frequency characteristic) of the filter represented by the N-th order rational transfer function is, as generally known, the cutoff frequency of the filter,
That is, with the vicinity of the pole of the transfer function as the center, (N / 2) π (r
ad) It changes. For this reason, as described above, when a waveform such as a single pulse waveform that exceeds the cutoff frequency of the filter is input to the filter, a time shift occurs for each frequency component, and the waveform after passing through the filter becomes time-dependent. Will be long.

In order to eliminate such a phenomenon, in order to eliminate the phase lag while maintaining the frequency characteristics of the filter, the transfer function H (ω) of the filter may be a real function. As described above, it is difficult to realize such a transfer function by the above-mentioned rational formula. This is the same in a recursive digital filter of the form in which equation (1) is discretized.

Therefore, in one embodiment of the present invention, a desired frequency characteristic is realized by configuring the linear phase filter with a moving average type digital filter. As is generally known, the inverse Fourier transform x (t) of the real function X (ω)
Is an even function, a filter whose phase delay is always zero over the entire frequency band has its impulse response h
The component of (t) at t <0 becomes non-zero, that is, non-causal and unrealizable. However, by providing a certain delay time α to the impulse response h (t) of this filter,

(Equation 2) Then, it becomes feasible. That is, a filter in which a constant delay constant α is added to an impulse response calculated by performing inverse Fourier transform on a desired frequency characteristic (cutoff frequency and steepness) may be configured.

The filter having the impulse response calculated as described above has a complicated configuration with analog elements.
Although difficult, it can be easily realized by using a moving average type digital filter in which the impulse response is discretized at a sampling period T. Also, the delay constant α
It is sufficient to use the time length (the number of samples in the case of digital operation) in which the impulse response of the filter sufficiently converges, and if the data length of the inverse Fourier analysis is L, it is 1 / (2L + 1). In the case of the present invention, preferably, L = 128T to L = 256T,
α = 65T to α = 129T.

The above procedure is based on a widely known Fourier transform formula,

(Equation 3) As is apparent from the above, after giving a linear phase component having a delay constant α as a coefficient to a desired frequency characteristic, h _a (t) is calculated by an inverse Fourier transform, and it is discretized to form a filter coefficient sequence. It is equivalent if found.

In general, a high-pass filter that performs a differentiation process is known to have a side effect of enhancing high-frequency noise. Therefore, when minute high-frequency noise is mixed in a load waveform, the H ( ω) at the same time as the low frequency component
A band pass characteristic that also cuts such unnecessary high frequency bands may be used.

In such a filter operation, the output waveform has a certain period of time compared to the input level, ie,

(Equation 4) Although it is delayed only by a sample, in the case of the above preferred example, the effect is small because it is as small as about 100 or more dozens of samples, and it is not necessary to correct it. However, this delay time is a known value. Therefore, the correction may be made.

Using the linear phase filter configured as described above, the load signal waveform shown in FIG.
Is processed as shown in the above, and the load fluctuation at the joining position is output without the disturbance of the waveform or the superposition of the burr portion. Therefore, for example, the minimum value of the waveform is obtained by a generally known minimum value search method. by calculating the time t _x which gives, it can be detected accurately and reliably joining position of the steel strip in the stand.

In order to search for the minimum value of the waveform as described above, the load signal from the force detecting means 10 is set so as to include the time when the joining position of the billet passes the final stage of the finishing mill 6. Set the start time and end time of the capture of data appropriately. For example, the take-in start time is set to the joining end time, and the take-in end time is set to a time obtained by adding the maximum time error to the expected rolling end time of the preceding rolled material.

Further, by using a steel strip speed detecting means such as a sheet speed meter or a measuring roll to accumulate the speed starting from the detected passing time of the joining point, the cutting device can be started from the exit side of the finishing mill 6. The joining position in the steel slab can be constantly tracked up to the entry side of 7. Specifically, the load start time of the load signal from the force detection means 10 is t ₀ , the load time length is t ₁ , and the load start time t _0.
Assuming that the time length from the time t to the minimum value detection time is t _x , and the sheet speed at the exit side of the finishing mill 6 is v (t), the distance D (t) of the joining position after passing through the exit side of the finishing mill 6 )

(Equation 5) It is represented by Therefore, if the cutting position of the steel strip is set based on the position information of the joining point represented by the above equation (4),
It is possible to cut accurately at a position desirable for operation.

[0028]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.
This will be described with reference to FIG. In one embodiment of the present invention, as shown in FIG. 1, the rolling load is detected as a voltage signal by a force detecting means 10 provided in the final stand of the finishing mill 6 of the continuous hot rolling equipment, and this rolling is performed. The load signal is supplied to a waveform analyzer 11 having a linear phase filter.

As shown in FIG. 2, the waveform analyzer 11
Amplifier 12, analog filter 13, A / D converter 1
4. It has a filter operation circuit 15, a storage device 16, and a waveform operation circuit 17 which constitute a linear phase filter (digital filter). The rolling load signal detected by the force detecting means 10 is amplified by an amplifier 12 to a voltage in an appropriate range of about 0 to 10 volts, and then the analog filter 1
After removing unnecessary band signals such as electromagnetic noise flying in the factory, the A / D converter 14 samples the voltage waveform at a constant sampling period T and outputs digital discrete data x. (I) and supplies it to the filter operation circuit 15.

In the filter operation circuit 15, discrete data x
(I) and a linear convolution operation expression of the filter coefficient sequence h (n) from the storage device 16,

(Equation 6) , And supplies the calculation result to the waveform calculation circuit 17. Note that the filter coefficient sequence h (n)
Are set as described above and stored in the storage device 16 in advance.

The waveform calculation circuit 17 searches the output of the filter calculation circuit 15 for a minimum value at an appropriate predetermined time length τ as described above, and calculates a time t _x .
It should be displayed on a display device (not shown) the calculated time t _x, and supplies to a higher process computer.

Next, a description will be given of a specific example of detecting the joining position during the continuous hot rolling operation in the above configuration. First, the specifications of the waveform analyzer 11 were set as shown in the table below.

[Table 1]

The waveform analyzer 11 having the above specifications includes:
When the load signal waveform shown in FIG. 3 detected by the force detecting means 10 was supplied, the output waveform shown in FIG. 4 was obtained from the filter operation circuit 15, and the joint position of the billet could be correctly detected. In addition, when the joining position was detected by applying the above-described plate bite detection method of differentiating the rolling load signal, a detection error occurred and a detection position error was about 6 m. On the other hand, in the above specific example, the detection error was 0 and the detection position error could be kept within 1 m.

As another specific example, the same detection was performed by changing the frequency characteristics of the digital filter (linear phase filter) in the above table to those having a band-pass characteristic of 20 Hz to 100 Hz. However, also in this case, the joining position could be correctly detected.

[0035]

According to the present invention, in continuous hot rolling, the joining position of a billet can always be detected with high accuracy without causing detection omission or overdetection. Therefore, it is possible to optimally set the coil cutting position when winding the continuous hot-rolled material, which can reduce material truncation and the like, improve the product yield, and prevent detection omission and overdetection of the bonding position. As a result, it is possible to effectively prevent the occurrence of defective coils and the occurrence of process troubles due to abnormal winding, thereby improving the productivity. Further, since the rolling load signal in the finishing rolling equipment can be obtained from a force detecting means such as a load cell usually installed in a rolling mill, it can be implemented simply and inexpensively.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of an example of a continuous hot rolling facility for implementing the present invention.

FIG. 2 is a block diagram showing a configuration of an example of a waveform analyzer shown in FIG.

FIG. 3 is a diagram showing an example of a load signal waveform obtained from a force detecting means of the finishing mill shown in FIGS. 1 and 2;

4 is a diagram showing an output waveform obtained by performing a filtering process on the load signal waveform shown in FIG. 3 according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Rough rolling machine 2 Entry side cutting device 3 Joining device 4 Lead rolling material 5 Trailing rolling material 6 Finishing rolling machine 7 Cutting device 8 Winding device 10 Force detecting means 11 Waveform analyzer 12 Amplifier 13 Analog filter 14 A / D conversion 15 Filter operation circuit 16 Storage device 17 Waveform operation circuit

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Makoto Okuno 1 Kawasaki-cho, Chuo-ku, Chiba City, Chiba Prefecture Inside the Technical Research Institute of Kawasaki Steel (72) Inventor Junzo Nitta 1 Kawasaki-cho, Chuo-ku, Chiba City, Chiba Prefecture Address: Kawasaki Steel Corporation Chiba Works (72) Inventor Kiyoshi Ueda 1 Kawasaki-cho, Chuo-ku, Chiba City, Chiba Prefecture Kawasaki Steel Corporation Chiba Works

Claims (2)

[Claims] 1. A joining position of a metal piece in continuous hot rolling in which a rear end portion of a preceding rolled material is joined to a leading end portion of a succeeding rolled material to continuously roll in a finishing rolling facility. In detecting the rolling load in the finishing rolling equipment, a high-pass type having a cutoff frequency and a steepness whose amplitude frequency characteristics are set in advance with respect to the rolling load signal, and the phase frequency characteristics are set in advance. A linear phase filter that is only a simple delay component determined by the determined delay coefficient is actuated, and the time to take the minimum value in a preset time section in the output signal of the linear phase filter is determined as the time of the preceding rolled material. A method for detecting a joint position of a metal piece in continuous hot rolling, wherein the method detects the joint position between a rear end portion and a front end portion of a succeeding rolled material. 2. The joining position detecting method according to claim 1, wherein the amplitude frequency characteristic of the linear phase filter is of a band-pass type. Method.