JP2007051918A - Flaw detection method of rolling material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a flaw detection method of a rolling material for accurately calculating the arrival time of the end part of the rolling material that arrives at a flaw detector, to accurately start or complete flaw detection. <P>SOLUTION: The average material passing speed Vave of the rolling material 3 that passes through a rolling machine 6 is calculated from the inlet side cross-sectional area Sin, outlet-side cross-sectional area Sout and outlet-side material passing speed Vout of the rolling material 3 in the rolling machine 6, the passing time Tio of the rolling material 3 that passes through the rolling machine 6 is calculated from the average material passing speed Vave and the distance Die from the inlet side of the rolling machine 6 to the outlet side thereof and the arrival time Tie of the rolling material 3, arriving at the flaw detector 12 after the end part of the rolling material 3, is detected on the upstream side of the rolling machine 6 is calculated, on the basis of the passing time Tio and the flaw detection due to the flaw detector 12 is started or completed after the arrival time Tie. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a flaw detection method for a rolled material rolled by, for example, a rolling mill.

Conventionally, in the rolling process of rolled material such as wire rods, a flaw detection device is arranged downstream of the finish rolling mill, a cooling device and a winding device are arranged downstream of the flaw detection device, and the rolling material is a winding device. Before being wound up, the flaw detection apparatus performs a flaw detection inspection on the surface of the rolled material.
In such a flaw detection inspection of a rolled material, if flaw detection is performed when the temperature of the object to be flawed (rolled material) is lower than the Curie point and the rolled material is in a ferromagnetic state, magnetic noise is generated and Usually, flaw detection of rolled material is not possible after rolling, because normal flaw detection is not possible if flaw detection cannot be performed stably or rolling material flaw detection is performed with the rolled material meandering after cooling with a cooling device. This is performed immediately after and before cooling with the cooling device.

For example, as shown in FIG. 10, the flaw detection apparatus causes a rolling material to pass through two coils to induce eddy currents on the surface of the rolling material, and the eddy current changes due to cracks on the surface of the rolling material. This is a phenomenon.
In the flaw detection apparatus, the impedance of the coil changes due to a change in eddy current, which causes an unbalanced voltage to be output between the terminals.
Now, considering the timing of starting the flaw detection of the rolled material with such a flaw detector, since flaw detection is performed immediately after rolling, the fact that the tip of the rolled material has entered the flaw detector is detected by an inrush signal etc. If flaw detection is started, it is considered that flaw detection can be performed from the front end portion of the rolled material to the rear end portion in order.

However, the rolling speed of the wire rod is very high at 80 m / sec. Therefore, if the flaw detection is started after the rush signal is detected, the flaw detection processing is not in time, or the flaw detection processing is in time. Even if the flaw detection device recognizes the tip of the rolled material as a large flaw, it is very difficult to distinguish between the rolling material entry signal and the flaw detection signal. There is a problem that it is not possible to start the flaw detection of the rolled material after detecting that the front end of the flaw has entered the flaw detection device by the rush signal.
Therefore, a method has been considered in which a tip detection sensor is arranged on the upstream side of the flaw detection apparatus, and the flaw detection of the rolled material is started after a predetermined time after the tip detection sensor detects the tip of the rolled material (for example, Patent Document 1).

Patent Document 1 is based on the idea that the tip of the rolled material is detected by a tip detection sensor before the rolled material reaches the flaw detection device, and the tip reaches the flaw detection device after a certain period of time has been detected. In addition, the timing for starting the flaw detection of the rolled material is determined, but when calculating the time to reach the flaw detection device after detection by the tip detection sensor, the rolling speed of the rolled material in the rolling mill is constant. It must be a condition.
JP 2001-305108 A

Usually, when rolling a rolling material with a rolling mill having a plurality of rolling stands, for example, the thickness of the rolling material is reduced for each rolling stand, so that the rolling speed changes for each stand.
Therefore, even if the time for the tip of the rolled material to reach the flaw detector is calculated with a constant rolling speed as in Patent Document 1, flaw detection cannot be started at an accurate timing that does not match the actual situation. is there.
As a method to solve this problem, the rolling speed between each stand is calculated based on the idea of the constant mass flow (the product obtained by multiplying the cross-sectional area of the rolled material by the rolling speed), and the elapsed time between each stand. By adding each of the above, by determining the passing time for the rolled material to pass through the rolling mill, it is possible to obtain a material that also considers the rolling speed change.

However, when the passage time is obtained according to the constant mass flow rule, it is necessary to calculate the rolling speed for all the stands, and there are many factors for calculation, and the calculation formula becomes complicated. In addition to this, considering that the rolling speed is as high as 80 m / sec and the above calculation process has to be very high, it is very difficult to calculate the passage time using the constant mass flow rule. .
Therefore, in view of the above problems, the present invention provides a rolled material flaw detection method capable of accurately calculating the arrival time at which the end of the rolled material reaches the flaw detection apparatus and accurately starting or ending flaw detection. The purpose is to do.

In order to achieve the above object, the present invention has taken the following measures. That is, the technical means for solving the problems in the present invention is a rolling material in which a flaw detection device is arranged on the downstream side of a rolling mill having a plurality of rolling stands and the rolled material rolled by the rolling mill is detected by this flaw detection device. In the flaw detection method of
The average passing speed of the rolled material passing through the rolling mill is calculated from the inlet side sectional area, the outlet side sectional area, and the outlet side passing speed of the rolled material in the rolling mill. From the distance from the side to the exit side, the passing time for the rolled material to pass through the rolling mill is calculated, and based on this passing time, the end of the rolled material is detected on the upstream side of the rolling mill and then the flaw detection device. The arrival time until it reaches is calculated, and the flaw detection device starts or ends after the arrival time.

The inventor has verified from various angles about setting the time for the end of the rolled material to reach the flaw detector with the simplest possible calculation. As a result, the entry side cross-sectional area, the exit side cross-sectional area, and the exit side speed of the rolled material can be obtained before the rolled material reaches the flaw detection apparatus or before rolling. We found the passage time and calculated the arrival time by this passage time. In addition, the entrance side cross-sectional area, the exit side cross-sectional area, and the exit side speed of the rolled material may be measured values, predicted values, or target values.
Therefore, it is possible to accurately and quickly calculate the arrival time until reaching the flaw detection apparatus, and to start or end the flaw detection of the rolled material with good timing.

  The passing time is calculated from [Expression 1] and [Expression 2].

The above [Equation 1] is derived from various experiments, and the average passing speed at which the rolled material passes through the rolling mill is the cross-sectional area ratio obtained by dividing the cross-sectional area after rolling the rolled material by the cross-sectional area before rolling. We found that it is proportional to the power of 1/2. When the average material passing speed and the distance from the entry side to the exit side of the rolling mill are known, the passing time can be calculated by [Equation 2].
As a result, it is possible to calculate the passage time from when the end portion of the rolled material is put into the rolling mill to when it is discharged, and to accurately start the flaw detection of the rolled material, and to accurately end the flaw detection of the rolled material. .

Another technical means of the present invention has a tip non-flaw detection portion that does not perform flaw detection by the flaw detection device at the tip portion of the rolled material, and the length of the tip non-flaw detection portion and the delivery-side material passing speed From this point, the non-defect detection time for the tip non-defect detection portion is calculated, and the flaw detection device starts flaw detection after the passage time and the non-defect detection time are added after the rolling material has entered the rolling mill. is there.
According to this, even if there is a tip non-flaw detection portion that does not perform flaw detection at the tip portion of the rolled material, the flaw detection of the rolled material can be started accurately.
According to another technical means of the present invention, a rear end non-flaw detection unit that does not perform flaw detection by the flaw detection device is provided at the rear end of the rolled material. From the material speed, the non-flaw detection time for the rear end flaw detection part is calculated, and after the rear end part of the rolled material enters the rolling mill, the flaw detection apparatus performs flaw detection after the time obtained by subtracting the non-flaw detection time from the passage time. The point is to end.

  According to this, even if there is a rear end non-flaw detection portion that does not perform flaw detection at the rear end portion of the rolled material, the flaw detection of the rolled material can be completed accurately.

  ADVANTAGE OF THE INVENTION According to this invention, the arrival time when the edge part of a rolling material reaches | attains a flaw detection apparatus can be calculated correctly, and flaw detection can be started or ended correctly.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
1-3 has shown the whole rolling apparatus which implements the flaw detection method of the rolling material of this invention.
Is shown.
As shown in FIGS. 1 and 2, this rolling device 1 is for rolling a rolled material 3 transferred from a heating furnace 2 into a wire rod (strip bar), a rough rolling mill 4, an intermediate rolling mill 5, and a finish rolling mill 6. A cooling zone 7 (cooling machine), a winder 8, and a control device 9 for controlling them.
A rough rolling mill 4 is disposed on the downstream side of the heating furnace 2, and an intermediate rolling mill 5, a finishing rolling mill 6, a cooling zone 7, and a winder 8 are sequentially disposed from the rough rolling mill 4 toward the downstream side. ing. A first end detection sensor 10 and a second end detection sensor 11 (end detection means) are disposed between the intermediate rolling mill 5 and the finish rolling mill 6, and the finish rolling mill 6 and the cooling zone are arranged. A flaw detection device 12 for flaw detection of the wire 3 is disposed between the two.

The first end detection sensor 10 and the second end detection sensor 11 are configured by an HMD (hot metal detector) that can detect the front end and the rear end of the wire rod by detecting infrared rays from the wire rod 3. ing.
That is, the first end detection sensor 10 and the second end detection sensor 11 can detect a high-temperature object. For example, when a high-temperature wire 3 of about 1000 ° C. passes through the sensor, the detection signal (ON signal) is output, and when the wire 3 does not pass, the detection signal is not output (OFF signal).

The first end detection sensor 10 is arranged on the upstream side of the second end detection sensor 11, and outputs a detection signal to the control device 9 when detecting the end of the wire 3. The second end detection sensor 11 is disposed on the entry side of the finish rolling mill 6, and outputs a detection signal to the control device 9 and the flaw detection device 12 when the tip of the wire 3 enters the finish rolling mill 6.
Each of the rolling mills 4, 5, 6 is a multi-stage rolling mill having a plurality of rolling stands 13 (work rolls), and the wire rod 3 is rolled to a predetermined size by the rolling stand 13. In the rolling apparatus 1 according to the embodiment, the wire 3 having a diameter of φ4.0 mm to φ20 mm can be manufactured in steps of about φ0.1 mm.

On the exit side of the finish rolling mill 6, a speed converter 14 that measures the roll peripheral speed in the final rolling stand 13 a in the finish rolling mill 6 and converts it into a rotation speed is arranged. The number of rotations is output to the flaw detector 12.
The flaw detection device 12 mainly detects a physical flaw or a metal flaw on the surface of the wire 3 and is arranged immediately after the exit side of the finish rolling mill 6. The flaw detection apparatus 12 is a hot-penetrating type, and includes a flaw detection control unit 15 and a head unit 16 (probe unit) that performs flaw detection of the wire 3, and a flaw detection start output from the flaw detection control unit 15. Based on the flaw detection end signal, the head unit 16 starts or ends flaw detection of the wire 3.

The control device 9 (process computer) controls, for example, the rolling load and roll peripheral speed of the rolling stand 13 or the cooling speed in the cooling zone 7, and the wire 3 to be rolled has a predetermined size. Each rolling mill 4, 5, 6 and the cooling zone 7 are controlled so that it may become.
Next, operation | movement of the rolling apparatus 1 and the flaw detection apparatus 12 is demonstrated using FIGS.
First, the wire 3 transferred from the heating furnace 2 is rolled into a wire 3 having a predetermined size via a rough rolling mill 4 and an intermediate rolling mill 5, and is transferred from the intermediate rolling mill 5 to the finish rolling mill 6.
As shown in FIGS. 2 to 4, the first end detection sensor 10 detects the tip of the wire 3 before the wire 3 enters the finish rolling mill 6, and when the detection signal is input to the control device 9, the control is performed. The apparatus 9 transmits the entry side sectional area Sin and the exit side sectional area Sout of the wire 3 transferred to the finish rolling mill 6 to the flaw detection control unit 15 of the flaw detection apparatus 12 based on the rolling data of the wire 3 to be rolled.

At this time, the number of rotations of the final stand 13a determined based on the rolling data of the wire 3 to be rolled is also input to the flaw detection control unit 15.
The flaw detection control unit 15 obtains the threading speed of the wire 3 in the final rolling stand 13 based on the number of revolutions in the final rolling stand 13, that is, the outgoing side passing speed Vout, and the outgoing side passing speed Vout and the incoming side interruption. From the area Sin and the exit cross-sectional area Sout, the average passing speed Vave of the wire 3 passing through the finish rolling mill 6 (until the wire 3 enters and exits the finish rolling mill 6) is calculated.
Further, the flaw detection control unit 15 calculates a passing time Tio for the wire 3 to pass through the finishing mill 6 based on the average material passing speed Vave, and the second end detection sensor 11 is used for the wire 3 based on the passing time Tio. The arrival time Tie from the detection of the edge portion to the flaw detection device 12 is calculated, and the arrival time Tie is stored.

In this embodiment, since the second tip detection sensor is disposed on the entry side of the finish rolling mill 6, the arrival time Tie enters the flaw detection device 12 after the tip of the wire rod 3 enters the finish rolling mill 6. It will be time until.
Then, when the second end detection sensor 11 detects the tip of the wire 3 and the detection signal is input to the flaw detection control unit 15, the flaw detection control unit 15 reaches the arrival time after the tip of the wire 3 is detected. After the tie, a flaw detection start signal is transmitted to the head unit 16. When the flaw detection start signal is input, the head unit 16 starts flaw detection of the wire 3.

When the second end detection sensor 11 detects the rear end of the wire 3 and the detection signal is turned OFF, the flaw detection control unit 15 detects the head portion after the arrival time Tie after the rear end of the wire 3 is detected. When the flaw detection end signal is transmitted to 16 and the flaw detection end signal is input, the head unit 16 ends the flaw detection of the wire 3. In this case, the arrival time Tie is a time from when the rear end of the wire 3 enters the finish rolling mill 6 until it enters the flaw detection apparatus 12, and the flaw detection of the flaw detection apparatus can be terminated after the arrival time.
As shown in FIG. 3, the entry-side cross-sectional area Sin is a cross-sectional area before the wire rod 3 enters the finish rolling mill 6, that is, when the wire rod 3 leaves the intermediate rolling mill 5, The calculated predicted value may be used, or the actual cross-sectional area may be measured with a sensor or the like and the cross-sectional area may be used.

The exit-side cross-sectional area Sout is a cross-sectional area when the wire 3 comes out of the finish rolling mill 6, and the cross-sectional area may be a predicted value calculated in advance, or an actual cross-sectional area is measured with a sensor or the like. Then, the cross-sectional area may be used.
The delivery-side material passing speed Vout is obtained from the rotational speed of the final rolling stand 13a. That is, a speed meter such as a laser Doppler type is disposed on the final rolling stand 13a side of the finish rolling mill 6, the passing speed of the wire 3 passing through the final rolling stand 13a is measured, and the rotation speed of the final rolling stand 13a By examining the relationship with the material passing speed in advance, the delivery side material passing speed Vout can be obtained from the rotation speed of the final rolling stand 13a.

  The average material passing speed Vave and the passage time Tio are calculated from [Formula 1] and [Formula 2].

The above [Formula 1] is derived by various experiments as will be described later, and the average passing speed Vave is the cross-sectional area after the rolling of the wire 3 (exit-side cross-sectional area Sout). It is proportional to the 1/2 power of the cross-sectional area ratio divided by the area (Sin).
Next, the process of deriving [Equation 1] will be described.
The inventor uses the two-stage finish rolling mill 6, the six-stage finish rolling mill 6, and the ten-stage finish rolling mill 6, each having a different number of rolling stands 13, to manufacture the wire 3 having a diameter of φ5.5 mm to φ20 mm, The rolling data of the passing time Tio, the exit side material speed Vout, the distance Dio from the entry side to the exit side of the finish rolling mill 6, the exit side sectional area Sout, and the entry side sectional area Sin were measured.

  Next, based on the rolling data obtained from the experiment, for each finish rolling mill 6, the distance Dio from the entry side to the exit side of the finish rolling mill 6 is expressed as the passage time Tio as shown in [Equation 3] below. The y value divided by the product of the delivery-side material feed speed Vout is calculated, and the X value obtained by dividing the delivery-side sectional area Sout by the entry-side sectional area Sin, that is, the sectional area, as shown in [Formula 4] below. Ratio values were calculated. Then, as shown in FIG. 5, these values were plotted with the y value calculated by [Expression 3] on the vertical axis and the x value (cross-sectional area ratio) calculated by [Expression 4] on the horizontal axis.

In addition, the product of the passage time Tio and the delivery-side material speed Vout in [Formula 3] indicates the length of the wire 3 that has passed through the finish rolling mill 6, and accordingly, the y value of [Formula 3] Indicates the ratio between the actual passing length of the wire 3 and the distance Dio from the entry side to the exit side of the finish rolling mill 6.
Here, the numerical values of three patterns obtained by calculating the x value (cross-sectional area) of [Expression 4] to the 1/1, 1/2, and 1/3 powers are calculated, and the numerical values of these three patterns and the y value are plotted. Plots were made as shown in 6 (a)-(c). And in each figure shown to Fig.6 (a)-(c), in order to obtain | require the regression line of the said plot value using the least squares method, the following [Formula 5]-[Formula 7] were prepared.

[Equation 5] is the primary approximation in FIG. 6A, [Equation 6] is the primary approximation in FIG. 6B, and [Equation 7] is the primary approximation in FIG. 6C. Further, as a result of the regression calculation, the primary approximation coefficients in the respective equations were A1 = 1.788, A2 = 1.030, A3 = 0.800.
Next, [Expression 3] is transformed into [Expression 8] below, and the y value obtained from [Expression 5] to [Expression 7] is substituted into [Expression 8], and [Expression 5] to [Expression 7] and The predicted transit time Tio was obtained from [Equation 8]. Further, the actual passing time Tio of the wire rod 3 is measured, and the predicted passing time Tio obtained from the y value of each of [Expression 5] to [Expression 7] and the actual passing time Tio are shown in FIG. Plotted as shown in (c).

FIG. 7A shows the predicted passing time Tio using the y value of [Expression 5], and FIG. 7B shows the predicted passing time Tio using the y value of [Expression 6]. FIG. 7C shows the predicted transit time Tio using the y value of [Equation 7].
As can be seen from FIG. 7, it is found that the predicted passage time Tio obtained with the y value of [Formula 6] is closest to the actual passage time Tio than that obtained by other equations.
Table 1 shows the prediction accuracy in each equation obtained, that is, the actual value (actual measurement value) of the passage time Tio and the correlation coefficient between each equation.

As can be seen from Table 1, when looking at the correlation coefficient between the actual value of the passage time Tio and each expression, the correlation coefficient for [Expression 6] is closest to 1.0, and [Expression 6] It turns out that what predicts Tio is the most reliable.
Next, since the length z that the wire rod 3 has passed through the finish rolling mill 6 can be expressed by the following [Expression 9], the y value obtained from [Expression 5] to [Expression 7] is expressed as [Expression 8]. By substituting, the predicted length that the tip of the wire rod 3 passes through the finish rolling mill 6 was obtained from [Formula 5] to [Formula 7] and [Formula 8]. Further, the actual length of the actual wire 3 passing through the finish rolling mill 6 was measured. Then, the difference between the actual length and the predicted length was calculated, and the difference between the actual length and the predicted length and the x value (cross-sectional area ratio) were plotted as shown in FIG.

  Further, when the standard deviation between the predicted length predicted by each formula and the actual length (measured length) was obtained, it was as shown in Table 2. As can be seen from this, it can be confirmed that the standard deviation is the smallest when predicted by the y value of [Expression 6]. The difference between the predicted length predicted by the y value of [Equation 6] and the actual length (measured length) is three times the standard deviation (3σ) or less, and when converted to the length of the wire 3, it is 1 m or less. Become.

As can be seen from FIG. 8 and Table 2, the predicted length when the cross-sectional area ratio is 1/2 power is the closest to the actual length.
As described above, the y value and the x value represented by [Expression 6] are closest to the actual values, and when [Expression 4] and [Expression 3] are substituted into [Expression 6], the following [Expression 6] 10].

  Here, when the above [Formula 10] is further arranged, the following [Formula 11] is obtained.

As shown in [Formula 11], when considering only the entry side and the exit side of the finish rolling mill 6, the average distance is obtained by dividing the distance Dio from the entry side to the exit side of the finish rolling mill 6 by the passage time Tio. Since it is considered that the material time is Vave, the average material passing time Vave can be represented by an exit side sectional area Sout and an entry side sectional area Sin. The above [Formula 11] is the same as the above [Formula 1].
According to the present invention, as shown in [Equation 1], the average material passing speed Vave is obtained by multiplying the sectional ratio obtained by dividing the exit-side sectional area Sout by the entrance-side sectional area Sin by multiplying the square root by the coefficient A. It can be obtained by multiplying the side material passing speed Vout.

  In this embodiment, since the flaw detection device 12 is arranged immediately after the exit side of the finish rolling mill 6, the distance Die from the exit side of the finish rolling mill 6 to the flaw detection device 12 is considered as 0, and the passing time Tio is reached. When the time Tie is the same, that is, Tio = Tie, the arrival time Tie can be obtained. Note that the flaw detection device 12 is not located immediately after the exit side of the finish rolling mill 6 but at a position away from the exit side of the finish rolling mill 6, and the distance Die from the exit side of the finish rolling mill 6 to the flaw detection device 12 is limited. In this case, the wire passing speed of the wire 3 in the meantime is considered to be the same as the delivery-side passing speed Vout, and can be obtained by the following [Equation 12].

Next, since a non-flaw detection portion that does not perform flaw detection is set in advance at the front end portion and the rear end portion of the wire rod 3 and the portion may be discarded without performing flaw detection, flaw detection is performed on the front end portion of the wire rod 3. Consider a case where no tip non-defect detection part is determined in advance.
As shown in FIG. 9A, it is assumed that the tip non-defect detecting portion 20 having a length Fh is provided at the tip of the wire 3.
In the case where the wire 3 has the tip non-defect detecting portion 20, even if the tip non-defect detecting portion 20 reaches the flaw detection device 12, the tip non-defect detecting portion 20 does not perform the flaw detection by the length Fh. The time for passing through the head portion 16 of the apparatus 12, that is, the non-flaw detection time is calculated. This non-flaw detection time can be calculated by Fh / Vout.

  The time Th for starting the flaw detection after the front end portion of the wire 3 enters the finish rolling mill 6 (in other words, the time for starting the flaw detection after the second end detection sensor 11 detects the front end portion) is as follows: 13].

Therefore, the non-flaw detection time for the tip non-flaw detection part 20 is calculated from the length (Fh) of the tip non-flaw detection part 20 and the delivery-side material passing speed Vout, and the tip part of the wire 3 enters the finish rolling mill 6. If the flaw detection apparatus 12 starts flaw detection after a time obtained by adding the passage time (Tio + Toe) and the non-flaw detection time after that, the flaw detection can be performed in order from the tip portion where flaw detection of the wire 3 is necessary. The inspection can be performed as much as the inspection is necessary without detecting the portion.
In addition, as shown in FIG. 9B, when the rear end non-detecting portion 21 has a length Ft at the front end portion of the wire 3, the length Ft even if the rear end non-detecting portion 21 reaches the flaw detection device 12. Since the flaw detection is not performed as much as that, the non-flaw detection time of the rear end non-flaw detection portion 21 is calculated. This non-flaw detection time can be calculated by Ft / Vout.

  The time Th for starting the flaw detection after the front end portion of the wire 3 enters the finish rolling mill 6 (in other words, the time for starting the flaw detection after the second end detection sensor 11 detects the front end portion) is as follows: 14].

Therefore, the non-flaw detection time for the non-rear end flaw detection part 21 is calculated from the length of the rear end non-flaw detection part 21 and the delivery-side material passing speed Vout, and the rear end part of the wire 3 enters the finish rolling mill 6. Thus, if the flaw detection apparatus 12 ends the flaw detection after a time obtained by subtracting the non-flaw detection time from the passage time (Tio + Toe), the inspection can be performed as much as flaw detection is required without flaw detection. .
As described above, since it is possible to accurately perform the flaw detection only on the portion where flaw detection is performed on the front end portion and the rear end portion of the wire rod 3, it is only necessary to cut off only a predetermined non-flaw detection portion. In addition to the part, it is no longer necessary to cut off extra parts that originally had to be flawed, and productivity can be improved.

The present invention is not limited to the rolling apparatus 1 shown above. That is, in the above description, the rolling device 1 for the wire 3 has been described, but the present invention can also be applied to a rolling device such as a thin plate.
Further, the flaw detection control unit 15 calculates the average material passing speed Vave, the passage time Tio, and the arrival time Tie, but the control device 9 may perform these calculations.
Moreover, although it has detected that the front-end | tip part and the rear-end part of the wire 3 reached | attained the finishing mill 6 with the said 2nd end detection sensor (end part detection means), it is not restricted to this, For example, a wire 3 may be detected by the rolling stand 13 (for example, load change applied to the rolling stand 13) or may be detected by other means. .

  In this embodiment, since the second tip detection sensor is arranged on the entry side of the finish rolling mill 6, the arrival time Tie enters the flaw detection device 12 after the tip of the wire 3 enters the finish rolling mill 6. Or the time from when the rear end of the wire rod 3 enters the finish rolling mill 6 until it enters the flaw detector 12.

1 is an overall view of a rolling apparatus using a rolled material flaw detection method of the present invention. It is an apparatus block diagram of a finish rolling mill vicinity. It is explanatory drawing of each parameter in a finish rolling mill. It is a time chart figure which performs a flaw detection. It is the figure which plotted x value and y value. It is the figure which plotted the numerical value which raised x value to the power of 1 / n, and y value. It is a figure which shows the relationship between an actual passage time and estimated passage time. It is a figure which shows the relationship between the difference of the length of a front-end | tip, and sectional area. It is a figure which shows the non-flaw detection part of a wire. It is a schematic block diagram of a flaw detection apparatus.

Explanation of symbols

1 Rolling device 3 Rolled material (wire material)
6 Finishing rolling mill 12 Flaw detector

Claims (4)

In the flaw detection method for a rolled material, a flaw detection device is arranged on the downstream side of a rolling mill having a plurality of rolling stands, and flaw detection is performed on the rolled material rolled by the rolling mill with this flaw detection device.
The average material passing speed of the rolled material passing through the rolling mill is calculated from the inlet side sectional area, the outlet side sectional area, and the outlet side passing speed of the rolled material in the rolling mill. A flaw detection device after calculating the passing time for the rolled material to pass through the rolling mill from the distance from the entry side to the outlet side and detecting the end of the rolled material on the upstream side of the rolling mill based on the passing time. A method for flaw detection of a rolled material, in which an arrival time until reaching f is calculated and flaw detection of the flaw detection apparatus is started or ended after the arrival time. The method for flaw detection of a rolled material according to claim 1, wherein the passage time is calculated from [Expression 1] and [Expression 2].

The tip of the rolled material has a tip non-flaw detection portion that does not perform flaw detection with the flaw detection device,
From the length of the tip non-defect detection part and the delivery-side material passing speed, a non-defect detection time during which no flaw detection is performed on the tip non-defect detection part is calculated, and the passage time after the tip of the rolled material enters the rolling mill. 3. The method for flaw detection of a rolled material according to claim 1, wherein flaw detection by the flaw detection apparatus is started after a time obtained by adding the time to the non-flaw detection time. The rear end portion of the rolled material has a rear end non-detection portion that does not perform flaw detection with the flaw detection device,
From the length of the rear end non-flaw detection part and the delivery-side material passing speed, calculate the non-flaw detection time without performing flaw detection on the rear end flaw detection part, and after the rear end part of the rolled material enters the rolling mill, 3. The method for flaw detection of a rolled material according to claim 1, wherein flaw detection of the flaw detection apparatus is terminated after a time obtained by subtracting the non-flaw detection time from the passage time.

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