JPH11123422A - Device for measuring forward rate of continuous rolling mill - Google Patents

Abstract

PROBLEM TO BE SOLVED: To estimate the forward rate of a device with high accuracy and to enable the device to be used for rolling control by setting a criterion for detecting the strip admission/strip extraction of a material to be rolled based on a value executing averaging processing and regression processing to the actual results of rolling at each rolling stand. SOLUTION: The admission/extraction of a sheet at each of rolling stands 11, 12 are detected with a sheet presence signal generating circuit 14 and a sheet presence signal is generated. The moving speed of a material 13 to be rolled between the rolling stands is determined by a speed calculating means (a roll feeding length calculating circuit 15 or the like). A forward rate is determined based on the moving speed of the material 13 to be rolled with a forward rate calculating circuit 16 provided on a forward rate estimating device. A criterion for detecting the strip admission/strip extraction of the material 13 to be rolled at the rolling stands is set based on a value executing the regression process or the averaging process to the actual result value of rolling at each of the rolling stands 11, 12 with the sheet presence signal generating circuit 14.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention measures the advance rate in a continuous rolling mill having a plurality of rolling stands for sequentially and continuously rolling a material to be rolled, without incorporating new sensors, with high accuracy. The present invention relates to an apparatus for measuring an advanced rate of a continuous rolling mill.

[0002]

[Related Background Art] When continuously rolling a material to be rolled using a continuous rolling mill having a plurality of rolling stands, in order to ensure the quality of a rolled product, the rolling conditions in each rolling stand must be mutually matched. It is necessary to properly control them in association with each other. In particular, it is necessary to prevent the material to be rolled from being loosened or overstretched between the rolling stands, and to stably perform rolling at each rolling stand.

In order to realize such control, it is important to grasp the advance rate fs at each rolling stand. The advance rate fs is an index indicating the lubrication state between the material to be rolled and the rolling rolls, and is a ratio [Vs / Vr−] of the rolling speed Vs of the material to be rolled and the roll speed Vr in the rolling stand.
1]. Incidentally, the advance rate fs can be optimized by adjusting the properties of the lubricating oil, for example.

If the estimation of the advance rate fs is erroneously set for the rolling conditions (for example, the peripheral speed of the rolling roll) at each rolling stand, when the leading end of the material to be rolled bites into the next rolling stand, for example, The material to be rolled becomes too loose or too tight between the rolling stands. Furthermore, when the material to be rolled is extremely loose or stretched, so-called draw-downs or breaks in the sheet occur, and the rolling itself is significantly hindered.

[0005] The above-mentioned narrowing means that the material to be rolled is loosened greatly between the rolling stands, and as a result, the shape of the material to be rolled becomes extremely bad, so that the leading end of the material to be rolled is folded. This is a phenomenon of being stuck between rolling rolls of a rolling stand in a state. When such a reduction occurs, the material to be rolled, which has a thickness of about twice the predetermined thickness, is bitten between the rolling rolls, so that the rolling stand is seriously damaged. In addition, sheet breaking is a phenomenon in which the tension acting on the material to be rolled between the rolling stands becomes excessive, and as a result, the material to be rolled is broken. When such a sheet break occurs, continuous rolling of the material to be rolled is impaired.

Therefore, conventionally, for example, JP-A-61-19
As shown in Japanese Patent No. 9508, an actual friction coefficient is obtained based on measured values of a delivery plate speed and a roll speed under a preset rolling condition, and the actual friction coefficient is calculated using a friction coefficient model formula. A method of calculating a friction coefficient under a new rolling condition based on the calculated rolling ratio fs and predicting an advanced rate fs corresponding to the calculated friction coefficient has been proposed. Further, as disclosed in Japanese Patent Application Laid-Open No. 2-55608, etc., the timing at which the material to be rolled enters each rolling stand is detected from changes in the thickness signal and rolling load at each rolling stand. A method has been proposed in which the moving time of the material to be rolled between the intervals is obtained, and the advanced rate fs is calculated according to the moving time.

[0007]

However, in the method of calculating the friction coefficient using the friction coefficient model formula,
It is necessary to consider the influence coefficient caused by different rolling conditions, and to learn the influence coefficient under various rolling conditions. For this reason, there is a problem that it is difficult to obtain the advanced rate simply and with high accuracy.

Further, as described above, the method of detecting the timing at which the material to be rolled enters each rolling stand from the change in the thickness signal and the rolling load to predict the advance rate is based on the technique used only when steel is rolled. It is intended for the one having a high load level and easily detecting a sheet entering / leaving of a material to be rolled into a rolling stand. For this reason, it is difficult to accurately detect the timing of the sheet entry when the load level changes slowly due to the sheet entry / extraction of the material to be rolled, such as when rolling aluminum. In addition, the level at which the rolling load is stabilized varies greatly depending on the type of the material to be rolled, the sheet width, and the sheet thickness, and it is not easy to determine at what point in time the sheet entry timing should be set. For this reason, there is a problem that the accuracy of detecting the moving time of the material to be rolled between the rolling stands, which is determined from the detection timing of the sheet entry, is low, and the advanced rate cannot be determined with high accuracy.

It has also been proposed to detect the moving speed of the material to be rolled by using a contact type or non-contact type speed sensor, and to obtain an advance rate as a ratio to the roll peripheral speed. However, this method is effective during steady rolling, but has a problem in that it is not possible to determine the advance rate of the leading end of the material to be rolled immediately after the material to be rolled is engaged in the rolling stand. Moreover, the moving speed of the leading end of the material to be rolled is not always equal to the overall moving speed of the material to be rolled. Further, there is a problem that the detection accuracy is affected by the shape of the leading end of the material to be rolled.

[0010] The present invention has been made in view of such circumstances, and its object is to enter a sheet into a rolling stand / plate without depending on the type and thickness of the material to be rolled. It is an object of the present invention to provide an advanced rate predicting apparatus for a continuous rolling mill, which can easily and accurately detect a slippage timing and can measure an advanced rate with high accuracy. In particular, the present invention relates to each rolling stand which is obtained as a rolling load detected by a load cell provided in a rolling stand of a continuous rolling mill, a load state of a mill drive motor, and the like without newly incorporating a detector or the like in the continuous rolling mill. From the information indicating the operating state of the plate, the material entering the plate at each rolling stand
It is an object of the present invention to provide an advanced rate predicting apparatus which detects the timing of stripping with high accuracy and predicts an advanced rate.

[0011]

In order to achieve the above-mentioned object, an apparatus for predicting the advance rate of a continuous rolling mill according to the present invention comprises information indicating the operating state of a plurality of rolling stands for sequentially and continuously rolling a material to be rolled. A plate presence detecting means for detecting a plate ingress / exit of the material to be rolled in each rolling stand and generating a plate presence signal, based on a time interval of occurrence of the plate presence signal corresponding to each rolling stand. The moving speed of the material to be rolled between successive rolling stands is determined, and the advance rate is determined based on the moving speed of the material to be rolled. It is characterized in that a criterion for detecting a sheet entering / leaving of a material to be rolled in the rolling stand is set based on a value obtained by regressing or averaging the values.

Preferably, the information indicating the operation state of the rolling stand includes a rolling load applied to a work roll of each rolling stand, a drive current of a mill drive motor for driving the work roll, a rotation speed of the mill drive motor, Using the roll balance force applied to the work roll or the tension applied to the louver roll provided between the rolling stands, the material to be rolled is obtained from the information under the criterion set based on at least one actual value of the information. This is characterized in that the detection of board entry / exit of the board is detected.

Further, as the actual value of the information indicating the operation state of the rolling stand, the information in a stable state after a lapse of a predetermined time τ1 after the judgment of the above information under the provisional standard and the detection of the plate intrusion is obtained. It is characterized by seeking. In other words, the present invention averages the actual values in the stable state of the information indicating the operation state of each rolling stand in the continuous rolling mill,
Alternatively, based on the values obtained by the regression processing, a criterion necessary for accurately judging the timing of sheet entry / exit of the material to be rolled into the rolling stand is set. It is possible to easily and accurately predict the advance rate without incorporating a new speed detector or the like.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an apparatus for predicting an advanced rate of a continuous rolling mill according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a schematic configuration of a continuous rolling mill and a device for estimating an advanced rate thereof. Reference numerals 11 and 12 denote [i] th stage in a plurality of (n-stage) rolling stands constituting the continuous rolling mill. And [i + 1] th rolling stand. Each of the rolling stands 11 and 12 continuously rolls the material to be rolled (strip) 13 from the upstream side thereof, and is provided at a distance Ls in the rolling direction.

Each of the rolling stands 11 and 12 is provided with a pair of work rolls 1 and 2 for rolling while sandwiching the material 13 to be rolled.
And a pair of backup rolls 3 and 4 for pressing these work rolls 1 and 2 from the outside, respectively. Reference numeral 5 denotes a load cell provided in each of the rolling stands 11 and 12, and the load cell 5 detects a rolling load on the material 13 to be rolled. The load cell 5 is basically operated by a load adjusting mechanism (not shown).
It is incorporated to control the rolling load on the material 13 to be rolled. Reference numeral 6 denotes a mill drive motor for rotating the work roll 1. The peripheral speed of the work rolls 1 and 2 is adjusted by controlling the operation of the mill drive motor 6.

Reference numeral 7 in the figure denotes a louver roll provided between the rolling stands for removing slack in the material 13 to be rolled. The tension applied to the material 13 to be rolled by the louver roll 7 is incorporated into the louver roll 7. This is detected by the tension sensor 8 that is used. 9 in the figure
Is a thickness sensor provided on the delivery side of the rolling stand to detect the delivery thickness of the material 13 to be rolled.

The advance rate predicting apparatus according to the present invention is basically incorporated in a continuous rolling mill having a plurality of rolling stands 11 and 12 each including the load cell 5 and the like as described above. For example, the rolling load detected by the load cell 5 of each of the rolling stands 11 and 12 is detected as information indicating the operation state, and the material to be rolled on the rolling stands 11 and 12 is determined from the change in the rolling load as described later. 13 is detected as a board approach,
A board presence signal generation circuit 14 for generating a board presence signal at the board entry detection timing is provided. Further, in the advance rate prediction device, the above-mentioned plate presence signal generation circuit 14
The arrival time t of the material 13 to be rolled between the continuous rolling stands 11 and 12 is obtained from the time interval of the presence signal of the sheet that is detected and generated by detecting the sheet intrusion at 1 and 12, and within this arrival time t, for example, From the rotation speed of the mill drive motor 6, the peripheral speed of the work rolls 1 and 2 and the roll feed length L _R (the feed length of the rolled material 13).
Is provided.

[0018] and provided forward slip predictor forward slip calculation circuit 16, a roll feed and the length L _R calculated as described above, in accordance with the distance Ls between the rolling stands described above, predict the forward slip fs Calculate. Specifically, the advance rate fs is obtained by setting the sheet speed (the feeding speed of the material 13 to be rolled) to Vs,
Defined the roll peripheral speed as _{fs = (Vs / V R)} -1 when the V _R, fs = by multiplying the arrival time t of the material to be rolled 13 between rolling stands 11,12 (Vs · t / V _R · t) can be equivalently converted as -1 = Ls / L _R -1. Thus in accordance with this formula, the prediction calculation of the forward slip fs based on the length L _R feed roll determined as described above.

Incidentally, the distance Ls is set to be equal to each work roll 1,1.
The distance between the centers of (2, 2), that is, a value specific to the continuous rolling mill. However, when the louver roll 7 is provided between the rolling stands 11 and 12, the tension is applied to the material 13 to be moved between the rolling stands 11 and 12 by the louver roll 7, so that the linearity of the movement locus is not guaranteed. The movement distance is corrected by the amount by which the movement locus is bent by the louver roll 7.

Here, the above-described signal generator 14 with a plate will be described in more detail.
Is a load cell 5 provided on each of the rolling stands 11 and 12
From the change in the rolling load detected by the above, the sheet entry of the material 13 to be rolled into the rolling stands 11 and 12 is detected. However, the change in the rolling load accompanying the entry of the material to be rolled is relatively smooth as shown in FIG.
It takes some time for the rolling load to stabilize. For this reason, it is generally difficult to accurately detect the timing of plate entry from the change in the rolling load.

Therefore, the plate presence signal generation circuit 14 according to the present embodiment determines the plate entry (biting) from the level of the rolling load under a preset temporary reference, and determines a predetermined time τ1 from the detection timing of the plate entry. The rolling load level over a predetermined time τ2 from the point in time when the rolling load is stabilized after passing through is collected as rolling results, and the rolling results are averaged to obtain the actual load (average load value) during rolling. ing. Then, by performing a coefficient process on the average load value, for example, by multiplying by a coefficient [0.5], a criterion (plate entry determination level) for determining the sheet entry is set based on the above-mentioned rolling performance. Has become.

Specifically, as shown in FIG. 3, for each of the rolling stands 11 and 12, a rolling load value detected by a load cell 5 provided in the rolling stand is input [Step S11], and the rolling is performed. It is repeatedly determined whether the load value exceeds the tentative reference value described above [Step S1
2]. When the rolling load value exceeds the tentative reference value, it is determined that the plate has entered, and the elapse of a predetermined time τ1 at which the rolling load is expected to be stable is waited [step S13].

Next, if a predetermined time τ1 has elapsed from the detection time point and the rolling load has become stable, the rolling load value is collected over a predetermined time τ2 in that state, and this is obtained as the actual rolling load. Averaging processing is performed [Step S14]. Then, based on the weighted average obtained in this way, the material 13 to be rolled in each of the rolling stands 11 and 12
A determination criterion for determining board entry is set (step S15).

Note that such determination criteria are set for each of the rolling stands 11 and 12. Further, it is needless to say that the determination of the sheet ingress under the determination criteria set as described above is used in the subsequent rolling process.
As described above, the rolling results to be averaged may be the rolling results collected in a plurality of rolling processes. In short, based on the rolling performance (rolling load value) in the steady state collected for each rolling stand,
A criterion for determining whether or not the material 13 to be rolled enters the rolling stand may be set.

According to the plate presence signal generating circuit 14 for detecting the timing of the plate material 13 entering the rolling stand under the judgment criteria set in this way, the plate member 13 enters the plate. Therefore, even if the rolling load changes slowly, the timing at which the rolled material 13 enters the plate can be detected accurately and reliably from the rolling load change. That is, since the judgment criteria are set based on the rolling performance in a state where the rolling load is stable, the material to be rolled at the rolling stand is not affected by the load response at the time of the sheet entry unique to the rolling stand. 1
It is possible to reliably detect the timing at which the plate 3 enters (bites in). And the board presence signal generation circuit 14
Board entry (biting) in each of the rolling stands 11 and 12
Is detected, a board presence signal is generated at the detection timing.

The above-described roll feed length calculating circuit 15
The roll feed length L _R between the continuous rolling stands 11 and 12 from the time interval t of generation of such a plate presence detection signal.
Is requested as follows. That is, as shown in FIG. 4, it is determined whether or not a plate presence signal is generated in the i-th rolling stand 11 [Step S21]. When the occurrence of the plate presence signal is determined, the roll feed amount is determined at that time. Is initialized [Step S22]. Next, the roll feed length _LR is integrated by, for example, integrating the drive pulse of the mill drive motor 6 detected from the time of the initialization (step S23).

The roll feed length _LR is integrated while determining whether or not a plate presence signal is generated at the next (i + 1) th rolling stand 12 [Step S2].
4], repeatedly executed until the occurrence of the board presence signal is detected. The (i + 1) when the occurrence of the plate there signals in the rolling stand 12 of the stage is detected, [Step S25] by storing the roll feed length L _R that as integrated as described above, the roll feed length L _R Calculation is completed.

Therefore, the roll feed length L _R obtained as described above is determined based on the presence of plate signal generated by accurately detecting the biting timing of the material 13 to be rolled in the continuous rolling stands 11 and 12. Since the measurement is performed, the detection accuracy is extremely high. Therefore, as described above, the precision of the advanced rate fs calculated by the advanced rate calculation circuit 16 based on the roll feed length L _R becomes very high, and
Here, under the advanced rate fs predicted with high precision, it is possible to execute high-precision rolling control, and to improve the quality of rolled products. Especially rolling stands 11,1
The rolling control can be executed by predicting the advance rate fs with high accuracy while effectively utilizing the output of the load cell 5 incorporated in the rolling control apparatus 2.

In the above embodiment, the criterion for sheet entry is set based on the average value of the rolling load. However, for example, as shown in FIG. 5, the change in the rolling load is approximated by a specific function form. If it is possible, the board approach may be determined based on the function form. That is, if the change (transition) of the rolling load can be approximated by a first-order lag function as, for example, P = Po {1−exp (−t / To)}, the actual result of the rolling load P is first subjected to regression processing. Thus, as shown by the broken line in FIG. 5, the change in the rolling load is approximated by a first-order lag function. The biting time (t = 0.63T) of the material to be rolled 13 is calculated based on the obtained coefficient of the first-order lag function, and based on the biting time, the timing of sheet entry is determined from the change in the rolling load. The detection may be performed, and the presence signal may be generated at that timing. Based on the plate presence signal generated in this manner, the advance rate f
Similar effects can be obtained by calculating s.

In place of the rolling load detected at each of the rolling stands 11 and 12, a load state of the mill drive motor 6 for driving the work rolls 1 and 2, for example, a change in the drive current and the number of revolutions, is used. May be detected. Specifically, the drive current of the mill drive motor 6 changes as shown in FIG. 6, for example, as the rolled material 13 bites in the rolling stand. Therefore, such a change in the mill drive current is collected as a rolling record, and the biting time is set under a function approximated as described above,
Even if the drive current of the mill drive motor 6 is determined on the basis thereof, it becomes possible to detect the timing at which the rolled material 13 is incorporated into the rolling stands 11 and 12 with high accuracy, as in the above-described embodiments. Further, it is of course possible to detect the biting of the rolled material 13 with higher accuracy while simultaneously detecting such a change in the mill driving current and the above-described change in the rolling load.

In addition, not only the change in the drive current of the mill drive motor 6 but also the change in the motor rotation speed accompanying the sheet entering and the sheet coming out of the material 13 to be rolled may detect the biting in the same manner. Needless to say. Furthermore, rolling stand 1
1, 12 work rolls 1, 2 and work rolls 1, 2
A roll balance cylinder 10 is provided between the backup rolls 3 and 4 as shown in FIG. The roll balance cylinder 10 prevents the work roll 1 from falling, and stabilizes the rolls 1, 2, 3, and 4. Then roll balance cylinder 10
The roll balance force acting on the rolled material 13 also changes due to the sheet entering and stripping of the material 13 to be rolled. By paying attention to the change in the roll balance force, similarly to the previous embodiment, the timing of the sheet entry can be adjusted with high accuracy. It becomes possible to detect.

In each of the above-described embodiments, the advance rate fs is determined by detecting the biting timing of the material 13 to be rolled in the rolling stands 11 and 12, but the stripping timing of the material 13 is detected. You may do it. In this case, as shown in FIG.
The advance rate fs may be predicted and calculated in accordance with (1) the detection timing of the stripping in the rolling stand 17 of the first stage and (i) the detection timing of the stripping in the rolling stand 11 of the stage.

That is, in a normal continuous rolling state, a mass flow balance is established before and after each of the rolling stands 17, 11, and 12, and the volume shift amount is the same. In addition, in continuous rolling, since there is almost no deformation in the width direction, it is sufficient for the mass flow balance to consider only the longitudinal direction, which is the direction of continuous rolling, and the thickness direction thereof.

[0034] Thus in this case, between the moving distance L _R 2 between the moving distance L and _R 1, exit side stand between the entry side stands in the rolling stand 11 of the (i) th stage, the ( i) when the plate thickness on the entry side and exit side of the rolling stand 11 of the stage was set to _{h1, h2, L R 2 =} L R 1 × (h1 / h2) become. Therefore, assuming that the distance Ls between the rolling stands is equal, (i) the advanced rate f in the rolling stand 11 of the tier
s _{is, fs = (Ls / L R} 2) is expressed as _{-1 = (Ls / L R 1} ) · (h2 / h1) -1, therefore (i-1) th stage (i) and the stage each Even when the timing of stripping of the rolling stands 17 and 11 is detected, the advanced rate fs can be similarly calculated with high accuracy.

The present invention is not limited to the above embodiments. For example, as shown in FIG. 9, the contact of the material 13 to the louver roll 7 is detected from the output of a tension detector 8 incorporated in the louver roll 7 provided between a plurality of rolling stands, A time difference between the entry detection timing and the contact detection timing of the material 13 to be rolled on the louver roll 7 may be determined. In this case, the prediction calculation of the advance rate fs is performed according to the time difference and the separation distance Lk between the rolling stand 10 and the louver roll 7. That is, the material 13 to be continuously rolled
The timing of the presence or absence of the material to be rolled 13 (sheet ingress / extraction or contact / separation) at a position serving as a reference in the rolling direction is detected on the basis of a judgment criterion set on the basis of the actual result. The advance rate fs may be predicted and calculated based on. In addition, the present invention can be variously modified and implemented without departing from the gist thereof.

[0036]

As described above, according to the present invention, the intrusion / extraction of the material to be rolled is detected based on the value obtained by averaging or regressing the results of rolling at each rolling stand of the continuous rolling mill. Criterion is set, so that the advanced rate can be predicted with high accuracy without using a special sensor for newly detecting the sheet entering / leaving of the material to be rolled, and used for rolling control. . In particular, since the rolling results are collected in a state where the rolling load and the load state of the mill drive motor are stable, and the above-described determination criteria are set by averaging the rolling results, the timing of the sheet entering and the sheet removing can be easily performed. The detection can be performed with high accuracy, and effects such as the low cost of the advanced rate prediction device can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an apparatus for predicting an advanced rate of a continuous rolling mill according to an embodiment of the present invention.

FIG. 2 shows changes in rolling load due to biting of a material to be rolled,
The figure which shows the setting concept of the determination standard for board presence detection.

FIG. 3 is a diagram illustrating a setting procedure of a determination criterion in a board presence signal generation circuit.

FIG. 4 is a diagram showing a procedure of an arithmetic processing operation in a roll feed length calculation circuit.

FIG. 5 shows changes in rolling load due to biting of a material to be rolled,
The figure which shows the relationship of the primary approximation characteristic.

FIG. 6 is a diagram showing a change in a load state (mill current) of a mill drive motor accompanying a bite of a material to be rolled;

FIG. 7 is a diagram showing an arrangement structure of a roll balance cylinder 10 used for detecting presence of a plate in a rolling stand.

FIG. 8 is a conceptual diagram for explaining the operation of an advanced rate prediction calculation based on detection of a missing plate.

FIG. 9 is a diagram for explaining the concept of processing of advanced rate prediction calculation using contact of a material to be rolled with a louver roll.

[Explanation of symbols]

 1, 2 work roll 3, 4 backup roll 5 load cell (rolling load detection) 6 mill drive motor 7 louver roll 8 tension detector 10 roll balance cylinder 11 rolling stand (i-th stage) 12 rolling stand ((i + 1) -th stage) 13 Rolled material 14 Plate presence signal generation circuit 15 Roll feed length calculation circuit 16 Advanced rate prediction circuit 17 Rolling stand ((i-1) th stage)

Claims (3)

[Claims] 1. An advanced rate measuring device which is incorporated in a continuous rolling mill having a plurality of rolling stands for sequentially and continuously rolling a material to be rolled, comprising: A plate presence detecting means for detecting a plate ingress / exit of the material to be rolled in the rolling stand and generating a plate presence signal, and a continuous rolling stand based on a time interval of generation of the plate presence signal corresponding to each of the rolling stands Speed calculating means for determining the moving speed of the material to be rolled between the two, and advanced rate measuring means for calculating the advanced rate based on the moving speed of the material to be rolled determined by the calculating means, wherein the presence of the plate is detected. The means is based on a value obtained by regression processing or averaging processing of the actual rolling values at each rolling stand, and determines a criterion for detecting a sheet entering / leaving of a material to be rolled at the rolling stand. Advanced measuring apparatus of continuous rolling mill, characterized by a constant. 2. The information indicating the operation state of the rolling stand includes a rolling load applied to a work roll of each rolling stand, a drive current of a mill drive motor that drives the work roll, a rotation speed of the mill drive motor, It consists of a roll balance force acting on a work roll or a tension acting on a louver roll provided between rolling stands, and the material to be rolled is obtained from the information under a criterion set based on at least one actual value of these information. 2. The apparatus for measuring the advance rate of a continuous rolling mill according to claim 1, wherein the apparatus detects a sheet entering / leaving of a sheet. 3. The actual value of the information indicating the operation state of the rolling stand is obtained as information after a lapse of a predetermined time after detecting the board intrusion by judging the information under a provisional standard. The apparatus for measuring an advanced rate of a continuous rolling mill according to claim 1.