JP4131843B2 - Chatter mark detector - Google Patents

Description

  The present invention relates to a thickness measuring device and a chatter mark detecting device for measuring the thickness of a plate-like object to be rolled by a rolling mill, and in particular, a laser thickness meter and a radiation thickness meter are integrated. The present invention relates to a plate thickness measuring device and a chatter mark detecting device.

  Conventionally, a radiation thickness meter has been mainly used as a thickness measuring device for a sheet rolled by a rolling mill. This radiation thickness meter includes an X-ray thickness meter using X-rays and a γ-ray thickness meter using γ-rays. As the thickness measurement accuracy of these thickness gauges, an accuracy of 0.1% is ensured, and it has been used without any trouble for the quality control of a normal plate thickness.

  However, there is a problem in the demand for further reducing the measurement resolution of the plate thickness measurement. That is, the sheet thickness that is long in the width direction of the rolled sheet and is generated at a constant pitch in the moving direction, such as chatter marks due to mechanical vibrations of rolling mills and roll marks generated due to deformation or damage of the rolling roll. Variations were difficult to detect because of insufficient measurement resolution.

  That is, in order to detect chatter marks and roll marks, the thickness measurement accuracy is 0.1%, the absolute value is several μs or less, and from the point of resolution that can respond to the fluctuation speed and shape of the moving plate, The measurement spatial resolution is 10 mm, and the response speed is required to be 1 ms or more.

  For example, when the rolling speed is 600 m / min, a thickness measuring device of 1 ms is required as the response speed in order to respond to 10 mm as the resolution in the rolling direction.

  As a method for detecting such a plate thickness variation, two X-ray thickness meters having a resolution superior to that of the γ-ray thickness meter are juxtaposed in the rolling direction at a predetermined interval, and There is a method for obtaining a thickness variation of chatter marks or the like from the difference (see, for example, Patent Document 1).

  In this method, since the spatial measurement resolution is 10 mmφ on the surface of the object to be measured, the X-ray beam diameter satisfies the minimum required value, but the response speed is 10 ms, so that satisfactory performance cannot be obtained in this respect. .

  Therefore, recently, in thickness measurement requiring high resolution, a laser thickness meter using a laser distance meter using a laser beam as shown in FIG. 5 is used instead of the radiation thickness meter. .

  In the figure, the thickness measurement by the laser type thickness meter is performed by sandwiching the object 11 to be measured between the upper and lower arms 14T and 14B of the C-shaped frame 14 and facing the laser distance meters 10T and 10B with a distance L therebetween. The laser light reflected from the laser light source unit 12 and irradiated on the surface of the object to be measured 11 is received by the CCD camera 13, and the distances Lt and Lb between the laser distance meters 10T and 10B and the object to be measured 11 are set. Each is calculated by the distance calculation unit 15.

  Then, in the thickness calculation unit 20, the thickness t of the object to be measured 11 is obtained by calculation from the following equation (1).

t = L- (Lt + Lb) (1)
As for the spatial resolution of this laser type thickness meter, it is easy to set the diameter of the laser beam to about 1 mmφ on the surface of the object to be measured 11 by an optical system. Also, the response speed can be set to 1 ms or more by securing the intensity of the laser beam to a predetermined intensity or more, and this system can satisfy the performance required for high resolution.

  However, in this laser type thickness meter 100, when the distance L between the arm portions 14T and 14B of the C-type frame 14 for fixing the laser distance meters 10T and 10B varies as the ambient temperature changes, as shown in the equation (1). There is a problem that this variation becomes a measurement error.

  On the other hand, a radiation thickness meter using X-rays or γ-rays is a method for measuring the thickness from a change in the amount of transmitted radiation of the object 11 to be measured. Only very small errors occur.

  This point will be described in detail with reference to FIG. This figure is a general configuration diagram of the radiation thickness meter 200. In the figure, a radiation detector 17 and a radiation generator 16 are disposed opposite to each other with the object to be measured 11 sandwiched between the arms 14T and 14B of the C-shaped frame 14, respectively.

  And the radiation irradiated from the radiation generator 16 permeate | transmits the to-be-measured object 11, the transmitted radiation dose is received with the radiation detector 17, and the change of this received light signal is calculated with the thickness measurement calculating part 21, Thickness measurement is performed.

  In such a radiation thickness meter 200, when the distance L between the radiation generator 16 and the radiation detector 1 fluctuates, the amount of change in the amount of received light emitted from the radiation generator 16 is the radiation detector. Since only the amount corresponding to the change in the solid angle of light received at 17 is changed, there is very little measurement error in this case.

That is, if this distance variation is Δd, the change in the solid angle of light reception is proportional to (Δd / L) ^2. For example, even when L = 500 mm and Δl = 0.1 mm, the measurement error is 0. It falls within a very small range of 04% or less. As described above, according to the radiation thickness meter, there is no problem with respect to the distance variation, but it is difficult to satisfy the performance in terms of measurement resolution as described above.
Japanese Patent Publication No. 5-87325

  As described above, when trying to measure the thickness and shape of chatter marks, which are important for rolling mills, the conventional radiation thickness meter is satisfactory, but the measurement accuracy is satisfactory. Insufficient resolution. On the other hand, the laser thickness meter satisfies the measurement resolution, but has a problem that the measurement error due to the distance fluctuation between the fixed support points of the laser distance meter is large and the thickness measurement accuracy on the order of several μs cannot be satisfied.

  In addition, the arm size is a relatively large structure having an arm length of 1000 mm and an arm interval of about 500 mm from the shape of the object to be measured and the dimensions of the thickness measuring device. For this reason, the C-frame is made as compact as possible, using a special metal such as amber with a low coefficient of thermal expansion, and its surroundings are covered with a heat insulating material so that it is less susceptible to changes in ambient temperature. In an installation environment used in the vicinity of a rolling mill, it is difficult to suppress the variation in distance between the support points to several μ or less.

The present invention has been made in order to solve the above problems, eliminating the influence of a measurement error due to distance variation between the support point of the laser rangefinder, a high resolution, Ru can be measured the shape of the plate thickness at and accurately and to provide a switch <br/> Yatamaku detector.

In order to achieve the above object, a chatter mark detection apparatus according to the present invention includes a C-shaped frame having arms that sandwich the upper and lower sides of a moving object to be measured, and a pair of arms disposed facing the upper and lower sides of the arms. By irradiating the surface of the object to be measured with a laser distance meter and measuring the distance between the laser distance meter and the surface of the object to be measured from the reflected light, the surface of the object to be measured is measured. A laser-type thickness meter for measuring the thickness, a radiation generator on one of the arm portions, and a radiation detector on the other arm portion are arranged opposite to each other, and the radiation generator is disposed on the surface of the object to be measured. A radiation thickness meter that irradiates radiation and measures the amount of radiation that has passed through the object to be measured to measure the thickness of the object to be measured; and the irradiation position of the laser light of the laser type thickness meter and the The irradiation position of the radiation thickness meter is the moving direction of the object to be measured. And fixedly juxtaposed to the arm so as to be at the same position in a direction perpendicular to the moving direction, and the output of the laser thickness gauge and the output of the radiation thickness gauge. A positional deviation correction unit that corrects a deviation of a measurement position in the moving direction of the object to be measured; The difference between the average value of the output and the average value of the output of the laser-type thickness gauge is obtained as a correction value, and the thickness of the laser-type thickness gauge after correction of misalignment is corrected by the correction value. It is characterized by comprising a calculating means and a periodic signal determining means for obtaining a periodic signal from the output of the thickness calculating means.

  According to the present invention, since the periodic signal is statistically determined from the output of the plate thickness measuring device with high resolution and high accuracy, a highly accurate chatter mark detection device can be provided.

  As described above, according to the present invention, the drift factor of the laser-type thickness meter having high resolution is obtained as a correction value by calculating the difference between the thickness signal of the radiation thickness meter and the laser-type thickness meter signal, Since the thickness signal of the laser thickness gauge is corrected, the drift factor of the laser thickness gauge is eliminated, and a plate thickness measuring apparatus with high resolution and high accuracy can be provided.

  Further, since the periodicity of the sheet thickness signal is statistically determined using such a sheet thickness measuring apparatus, chatter marks having various frequencies by a rolling mill can be detected with a high S / N ratio.

  Furthermore, a periodic roll mark generated due to damage of the same rolling roll can also be detected.

  Examples 1 and 2 will be described below.

  A first embodiment of the present invention will be described with reference to FIGS. In the plate thickness measuring device 50 of the present invention, the laser thickness meter 2 and the radiation thickness meter 3 are integrally fixed to a C-shaped frame having a structure sandwiching the moving object to be measured 11 at a distance L. A thickness gauge detection unit 1 and a position deviation correction means 2 a that corrects a position deviation of signals between the laser thickness gauge 2 and the radiation thickness gauge 3 arranged in the direction of movement of the object to be measured 11 are provided.

  And the thickness roll which detects the moving speed of the thickness calculating part 4 and the moving to-be-measured object 11 which mention later the detail which calculates | requires thickness from the output of the laser-type thickness meter 2 and the radiation thickness meter 3 after position shift correction | amendment And a speed detector 7 connected to six shafts.

  Next, the detailed configuration of each part and the respective settings will be described in the case where the plate thickness of the DUT 11 is measured in the rolling line. The configuration of the thickness meter detection unit 1 includes a laser type thickness meter 2, a radiation thickness meter 3, and a C-type frame 14a that integrally accommodates both thickness meters.

  FIG. 2 is an exploded perspective view of the thickness meter detection unit 1 in which the laser thickness meter 2 and the radiation thickness meter 3 are mounted on the C-type frame 14a. Each thickness meter has a thickness calculation unit (not shown), but the thickness calculation unit is mounted on the C-type frame 14a or is disposed outside the C-type frame 14a. There is.

  In FIG. 2, a laser thickness meter 2 includes laser distance meters 10T and 10B and a thickness calculator (not shown). The laser distance meters 10T and 10B are an upper arm portion 1T and a lower arm portion 1B of a C-type frame 14a. Are opposed to each other with the object to be measured 11 interposed therebetween.

  These laser distance meters 10T and 10B are previously aligned and fixed on the surface of the object to be measured 11 so that the respective laser beam irradiation positions P1 coincide.

  The radiation thickness meter 3 includes a radiation generator 16, a radiation detector 17, and a thickness calculation unit (not shown). The radiation generator 16 and the radiation detector 17 include the lower arm portion 1B of the C-type frame 14a, The upper arm 1T is disposed opposite to the object to be measured 11 at the radiation irradiation position P2 of the radiation with the optical axis of the radiation aligned.

  The distance between the upper arm portion 1T and the lower arm portion 1B is a space dimension that allows the object to be measured 11 to pass through without any trouble even if it swings up and down, and further, a laser distance meter 10T for obtaining a predetermined thickness accuracy, For example, in the case where the measurement range of the object to be measured 11 is about 0.1 to 8 mm, the thickness is 200 mm so that the minimum dimension can be obtained from the optical dimension of 10B and the optical dimension of the radiation thickness meter. Or the dimension is set to about 500 mm.

  Further, the lengths of the arm portions 14T and 14B are determined by the plate width dimension of the object to be measured 11 and the measurement position in the width direction. Usually, the plate width dimension of the object to be measured 11 is within the range of the plate thickness. Since it is in the range of 800 mm to 2000 mm, in order to be able to measure the central portion of the plate width, the dimensions of the arm portions 14T and 14B of at least about 1500 mm are set.

  Such a structure of the C-shaped frame 14a may be a conventional radiation thickness meter structure in which the variation in the distance between the arm portion 14T and the arm portion 14B falls within a predetermined measurement error range in the radiation thickness meter 3. It is not necessary to set in consideration of suppressing an error due to a variation in the distance between the arm portion 14T and the arm portion 14B of the laser thickness gauge 2.

  Next, the setting of the speed signal synchronized with the movement of the DUT 11 supplied to each part of the plate thickness measuring device 50 will be described. As shown in FIG. 1, the speed detector 7 adjusts the gear ratio of a pulse transmitter or the like mechanically connected to the rolling roll 6 so as to obtain a distance resolution in a predetermined movement direction, for example, The pulse transmission ratio is set to about 1 mm / pulse.

  This speed detector 7 can also be generated by a laser velocimeter that measures the moving speed of the non-measurement object 11 in a non-contact manner.

  The speed signal s3 from the speed detector 7 is supplied to a positional deviation correction circuit 2a, a thickness maintenance calculation unit 4 and a periodicity determination unit 5, which will be described later, and is used as a unit length signal in the movement direction.

  Next, the setting of the misalignment correction circuit 2a will be described with reference to FIG.

  Since the output of the laser thickness meter 2 and the measurement position of the radiation thickness meter 3 are set at intervals of Lr in the movement direction of the object 11 to be measured, in order to match the measurement position, it is upstream in the movement direction. The output signal s1 of the laser thickness meter 2 is shifted to the position of the output signal s2 of the radiation thickness meter 3 by the speed signal (hereinafter referred to as a unit length signal) s3 to be matched.

Next, the thickness calculator 4 will be described with reference to FIG. The thickness calculator 4
An average circuit 41 for moving and averaging the output signal s1 of the laser thickness meter 2 by a unit length signal s3 in the moving direction by a predetermined length, and the output signal s2 of the radiation thickness meter 3 by a predetermined length. An averaging circuit 42 for moving average, a subtracting circuit 43 for calculating a difference between the output signal s5 of the averaging circuit 41 and the output signal s6 of the averaging circuit 42, and the laser thickness meter 2 after the positional deviation correction. An adder circuit 44 that adds the output signal s7 of the subtractor circuit 43 to the output signal s4 to obtain the thickness signal s8.

  The operation of the plate thickness measuring apparatus 50 configured as described above will be described with reference to FIGS. The chatter mark and the roll mark are generated as a thickness variation of a constant pitch Lr on the surface of the object 11 to be measured, for example, as shown in FIG.

  FIG. 4 shows signal waveforms at various parts of the thickness calculator 4 shown in FIG. 3 when the DUT 11 having such a thickness variation passes through the laser thickness meter 2. For example, the variation of the thickness signal corresponding to FIG. 5A is detected at a constant period T (= 1 / f).

  When the ambient temperature of the laser thickness gauge 2 changes and the distance between the arm portion 14T and the arm portion 14B varies, drift ed is generated. For example, as shown in FIG. The signal s1 is obtained by superimposing the drift component ed on the fluctuation.

  The output signal s1 of the laser thickness gauge 2 is made to coincide with the measurement position of the output signal s2 of the radiation thickness gauge 3 via the position deviation correction circuit 2a, and the thickness signal s4 of the laser thickness gauge 2 is obtained. Is input to the arithmetic unit 4.

  Normally, the output signals s1 and s2 are output as the absolute value thickness of the DUT 11 or the thickness deviation from the reference plate thickness value. Here, unless otherwise specified, each output signal s1, s2 will be described as a thickness deviation value.

  Next, the output signal s2 of the radiation thickness meter 3 will be described. The spatial resolution of the radiation thickness meter 3 is 10 times larger in the case of the X-ray thickness meter and 50 times larger in the case of the γ-ray thickness meter than the 1 mmφ of the laser thickness meter 2. As a result, the output signal s2 becomes a signal with a gentle response averaged over this spatial dimension as compared with the thickness signal s4.

  Further, even if the ambient temperature of the radiation thickness meter 3 changes and the distance between the arm portion 14T and the arm portion 14B varies, the variation error appears very little as shown in FIG.

  Accordingly, the signals s5 and s6 obtained by moving and averaging the output signals s1 and s2 by the averaging circuits 41 and 42 with a predetermined length are substantially linear as seen in FIGS. 4 (c) and 4 (e). .

  When the difference between the moving average signals s5 and s6 is obtained by the subtraction circuit 43, the drift component ed due to the distance between the arm portion 14T and the arm portion 14B by the laser thickness gauge 2 is detected as a correction value.

  Then, when the output of the subtracting circuit 43 is added to the thickness signal s4 of the laser thickness meter 2 after the positional deviation correction by the adding circuit 44, a thickness signal s8 from which the drift component ed has been removed is obtained.

  As described above, according to the first embodiment, the measurement error (drift component ed) due to the distance between the arm portion 14T and the arm portion 14B, which is an error factor of the laser thickness meter 2, is the radiation thickness meter. 3 is detected by calculating the difference from the thickness signal s4 of the difference laser type thickness meter 2, the drift error of the laser type thickness meter 2 is eliminated, and high accuracy, A high-resolution plate thickness measuring device can be provided.

  In addition, since the deviation of the measurement position between the laser thickness meter 2 and the radiation thickness meter 3 is corrected and the thickness calculation is performed by obtaining the difference between the respective plate thickness signals, depending on the difference in the measurement position Even if there is a difference in plate thickness, the difference is eliminated.

  The second embodiment is a chatter mark detecting device 60 using the plate thickness measuring device 50 according to the first embodiment, and will be described with reference to FIGS. The chatter mark detection device 60 uses the fact that the chatter mark is generated by fluctuations of various plate thicknesses at regular intervals due to vibrations of the rolling mill. Is detected by improving the S / N ratio by statistical processing from the output of the plate thickness measuring device 50 described above.

  The second embodiment is different from the first embodiment in that a periodicity determination unit 5 for inputting the thickness signal s8 and the speed detection signal s3 of the thickness calculation unit 4 is provided. Since the plate thickness measuring device 50 is the same as that described in the first embodiment, the description thereof is omitted.

  The periodicity determination unit 5 performs a Fourier transform on the thickness signal S8 in a predetermined period, thereby generating a peak value of the power spectrum at a chatter mark generation frequency f as shown in FIG. Is determined by comparing the power spectrum with a predetermined reference value set in advance.

  When the pitch at which chatter marks are generated is known in advance, the periodicity determination process can be detected by improving the S / N ratio by a synchronous addition process.

  This synchronous addition processing is performed by providing a storage circuit capable of writing for each unit length in the moving direction of a predetermined object to be measured 11, and adding by synchronizing the addition cycle of this storage circuit with the chatter mark cycle. Chatter marks are determined from the peak value of the signal that matches the period.

  As described in detail above, the plate thickness measuring device 50 and the chatter mark detecting device 60 of the present invention are not limited to the respective embodiments, and the distance measuring method of the laser distance meter of the laser type thickness meter, the radiation It is possible to change the thickness gauge measurement method without departing from the gist of the present invention.

The block diagram of a plate | board thickness measuring apparatus and a chatter mark detection apparatus. The perspective view of a detection part. The detailed block diagram of a thickness measurement part. The signal processing function explanatory drawing of a plate | board thickness measuring apparatus and a chatter mark detection apparatus. The block diagram of a laser-type thickness meter. The block diagram of a radiation thickness meter.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Thickness meter detection part 2 Laser type thickness meter 2a Position shift correction circuit 3 Radiation thickness meter 4 Thickness calculation part 41 Averaging circuit 42 Averaging circuit 43 Subtraction circuit 44 Addition circuit 5 Periodicity judgment part 6 Rolling roll 7 Speed detector 10T, 10B Laser distance meter 11 Object 12 Laser light source 13 CCD camera 14, 14a C-type frame 14T, 14B Arm 15 Distance calculator 16 Radiation generator 17 Radiation detector 20 Thickness calculator
21 Thickness Calculation Unit 50 Laser Thickness Meter 60 Radiation Thickness Meter 100 Laser Thickness Meter 200 Radiation Thickness Meter

Claims (3)

A C-shaped frame having arms that sandwich the top and bottom of the moving object to be measured;
The surface of the object to be measured by a pair of laser rangefinders arranged opposite to the top and bottom of the arm part
A laser beam is irradiated on the surface of the object to be measured between the laser distance meter and the surface of the object to be measured.
A laser-type thickness meter that measures the thickness of the object to be measured by measuring various distances;
A radiation generator is disposed on one arm and a radiation detector is disposed on the other arm so as to face each other.
The amount of radiation that has been irradiated from the radiation generator onto the surface of the object to be measured and has passed through the object to be measured
A radiation thickness meter to measure the thickness of the object to be measured
With
The irradiation position of the laser beam and the irradiation position of the radiation thickness meter of the laser thickness gauge are the measured values.
This is the same for a predetermined distance in the moving direction of the fixed object and in a direction perpendicular to the moving direction.
Fixed juxtaposition to the arm so that it is in the same position,
The output of the laser thickness gauge and the output of the radiation thickness gauge in the moving direction of the object to be measured.
Misalignment correcting means for correcting misalignment of the measurement position,
For the output of the laser-type thickness meter and radiation thickness meter corrected for the displacement, the radiation
The difference between the average value of the wire thickness gauge output and the average value of the laser thickness gauge output is obtained as a correction value.
, Thickness calculation that corrects the output of the laser-type thickness meter after correction of position deviation with the correction value
Means,
Periodic signal determining means for obtaining a periodic signal from the output of the thickness calculating means;
A chatter mark detection apparatus comprising: The periodic signal determining means is an output of the thickness calculating means synchronized with a moving distance of the object to be measured.
A Fourier transform circuit for calculating the frequency spectrum of
Chatter mark that determines the chatter mark by comparing the output of the Fourier transform circuit with a predetermined value
With the judgment circuit
The chatter mark detection apparatus according to claim 1, further comprising: The periodic signal determining means outputs the output of the thickness calculating means synchronized with the moving distance of the object to be measured.
A synchronous addition circuit that repeatedly adds at a fixed chatter mark generation distance period;
The chatter mark determination is performed by comparing the output of the synchronous adder circuit with a predetermined value to determine the chatter mark.
Constant circuit
The chatter mark detection apparatus according to claim 1, further comprising:

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