JP2006189315A - Optical shape measurement method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a simple measurement method for minutely measuring a true shape of a strip-shaped body in its entirety, the body moving at a high speed with its height varying. <P>SOLUTION: According to this shape measurement method of an optical cutting mode, a linear laser light source with its output modulated is used to form an optical cut image on the strip-shaped body, and a linear sensor of a delay integration type is used on the imaging side to perform overlap-imaging while shifting the cut image bit by bit, thus restoring the shape of the strip-shaped body. In this method, a widthwise position including only vibration components is searched for and a lengthwise height variation of a plate at this position is subtracted from a shape including vibration to remove the vibration, thereby measuring an original shape. Further, wave pitches are found from a change in the length of a widthwise cross-sectional curve while finding an elongation percentage from the length of a longitudinal height curve of the plate to simply calculate a wave height by sine-wave approximation. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for optically measuring the shape of a strip that runs at high speed.

For example, in a production line for hot-rolled steel sheets, it is important for quality control to measure shapes such as flatness of the steel sheets.
First, an index representing a shape such as flatness appearing on a steel plate that is one of strips that move in the longitudinal direction, which is a measurement target of the present invention, will be described.
Fig. 13 is an example of a shape defect when manufacturing a steel sheet, where (a) is called middle elongation, (b) is called an ear wave, and (c) is called second elongation (Quarter Buckle). The elongation at the center, end and quarter points appear as waves. Although FIG. 13 shows an example in which the ear waves and the second elongation appear on both sides in the width direction of the steel sheet, there are cases where they appear only on one side.
Wave height, wave pitch, steepness, and elongation are often used as indices representing the flatness of a steel sheet.

図15を用いて伸び率の定義を説明する。長手方向の長さL₀の測定範囲における鋼板の波曲線の長さをL、伸び率εは（２）式のように伸びL−L₀とL₀の比として定義される。

長さL₀の測定範囲をN個の有限区間に分けて、添え字を区間iに対応させると、長手方向位置の座標あるいは時刻をｔ、鋼板の波曲線の高さをｙとして、鋼板の波曲線の長さLは曲線の（３）式のように計算できる。

The definition of wave height, wave pitch, and steepness will be described with reference to FIG. When the steel plate 1 is placed on a flat table without applying tension, the difference between the heights of the wave peaks and valleys appearing in the longitudinal direction is the wave height P, and the pitch between the peaks and peaks or the valleys and valleys is the wave pitch. Define as P. The steepness λ is defined by the expression (1) as the ratio between the wave height H in the longitudinal direction of the steel sheet 1 and the wave pitch P.

The definition of the elongation rate will be described with reference to FIG. The length of the wave curve of the steel sheet in the measurement range of the length L _{0 in} the longitudinal direction is L, and the elongation rate ε is defined as the ratio of the elongations L−L ₀ and L ₀ as in equation (2).

If the measurement range of length L ₀ is divided into N finite sections and the subscript corresponds to section i, the coordinate or time of the longitudinal position or time is t, the height of the wave curve of the steel sheet is y, The length L of the wave curve can be calculated as in equation (3) of the curve.

この場合、計算範囲L₀を波ピッチPにとると、正弦波曲線の長さは、波の一周期分に関して（５）式のように計算できる。

鋼板の形状に関しては、波高さHはピッチPに比べ小さい、すなわち急峻度をλとするとλ=H/P << 1という仮定は十分な精度で成り立つので正弦波曲線の長さは（６）式のように計算できる。

計算範囲L₀は波ピッチPであるから伸び率εは（７）式のように表される。

したがって急峻度λは（８）式のように計算できる。

In order to convert between the steepness and the elongation rate, an elongation rate calculated by regarding the wave curve of the steel sheet as a sine wave may be used. FIG. 16 shows a case where the wave curve f (t) is a sine wave having a wave height H and a wave pitch P, and the wave curve is expressed by the following equation (4).

In this case, if the calculation range L ₀ is the wave pitch P, the length of the sine wave curve can be calculated as in equation (5) for one wave period.

Regarding the shape of the steel sheet, the wave height H is smaller than the pitch P. That is, assuming that the steepness is λ, the assumption that λ = H / P << 1 holds with sufficient accuracy, so the length of the sine wave curve is (6) It can be calculated as

Since the calculation range L ₀ is the wave pitch P, the elongation rate ε is expressed as in equation (7).

Therefore, the steepness λ can be calculated as shown in equation (8).

It is important in quality control to measure the above steel plate shape index.
When measuring the shape of a strip that runs at high speed, such as hot-rolled steel sheets, a number of laser displacement meters are arranged in the width direction and longitudinal direction of the steel sheet, and the C warp in the width direction of the steel sheet, or the ears in the longitudinal direction. A method of measuring a shape such as a wave or a medium stretch is known (Patent Document 1). However, even if a large number of laser displacement meters are arranged, the laser displacement meters are expensive, and there are at most several measurement points in the width direction. Further, when the plate width is changed or the plate meanders, a mechanism that follows the movement of the plate is also required.

On the other hand, in the method of measuring the shape of the belt-like body by the light cutting method combining the linear laser light source and the delay integration type linear sensor as in the method disclosed in Patent Document 2, the shape of the belt-like body running at high speed is used. Can be measured closely in the width direction and longitudinal direction, and the obtained shape can be imaged and shapes such as ear waves and medium stretch can be displayed in a visually clear form, and laser displacement Compared with the method of arranging a large number of meters, it is much cheaper and can realize highly accurate shape measurement with a small number of parts.

By the way, in the actual plate passing condition of the steel plate, the fluctuation in the height of the steel plate due to the vibration of the production line enters as a measurement error, as if a wave as a shape such as a middle stretch or an ear wave appears. There was a problem of giving an impression to the field operator. In Patent Document 3, by using two pairs of imaging means consisting of the linear laser light source and the delay integration type linear sensor, and taking the difference between the respective light cut images, the height fluctuation such as torsional vibration of the steel sheet is obtained. A method for measuring the shape of an unaffected true strip is disclosed. However, since the two pairs of image pickup means are used, the image pickup unit becomes large and it is difficult to adjust the position and the like. Also, depending on the production line, the torsional vibration of the steel sheet can be ignored, and it is only necessary to eliminate evenly uniform vibration in the width direction. There is a problem that the equipment is more expensive than the purpose of the application target at a level where it is only necessary to provide guidance to the field operator as to whether or not it has come out.
JP-A-5-1912 Japanese Patent No. 2913903 JP 2004-226240 A

When using a pair of imaging means, if the amplitude or period of the steel plate vibration is smaller than the wave height or pitch, the effect of vibration can be removed from the measured values of the wave height or pitch by using a smoothing filter. It is difficult to remove the influence of vibration by the smoothing filter when the amplitude and period of the wave are comparable. Also, as the thickness of the steel plate increases, the wave pitch tends to increase, and in order to measure the wave height and pitch, a long-period time window must be provided to obtain information on the wave apex. However, there is a problem that the measurement error increases because the period of the wrinkles and the wave period that occur when the steel sheet is unrolled may be approximated or the plate may be deformed in the middle.
In view of such a problem, the present invention measures the shape index of the band (hereinafter also referred to as a shape) with simple equipment over the entire length even if the height of the band due to the vibration of the production line occurs. An object is to provide a method that can be used.

In the following, a case where the change in the shape of the strip is measured as a change in height will be described by taking as an example the arrangement of the strip moving on a horizontal flat plate in the production line. Of course, the height may be read as displacement.
The first invention of the present application uses a linear laser light source whose output is modulated, and projects a linear laser beam on the strip in the width direction of the strip to form a light cutting curve (image). A light-cutting shape measuring method for reconstructing the shape of a band-like body by overlappingly imaging the light-cutting curve (image) on the band-like body by using a delay integration type linear sensor while shifting by a predetermined interval. , Obtaining a point in the width direction of the strip that minimizes the height variation along the longitudinal direction of the strip, and using the height variation in the longitudinal direction at the point as the magnitude of vibration of the strip In this optical shape measuring method, the index of the shape of the band-like body is measured over the entire surface or a part of the band-like body by subtracting from the height measured at each point in the direction.

In a second aspect of the invention, the shape index is any or all of wave height, wave pitch, steepness, and elongation rate, with the change in position of the shape of the band-like body being referred to as a wave. It is an optical shape measuring method.
According to a third aspect of the present invention, in order to obtain the index of the shape, a procedure for calculating the length of the longitudinal section curve at a plurality of discrete points x in the width direction of the strip, a step of length to find the point x _m in the width direction becomes a minimum, the procedure for calculating the elongation at each point x in the longitudinal section with respect to the length width direction of the curve at the point x _m A procedure for calculating the length of the light cutting curve on the surface of the strip at a plurality of discrete points t in the longitudinal direction, and the change of the length of the light cutting curve in the longitudinal direction An optical system comprising: a procedure for calculating the wave pitch from the interval; a procedure for calculating the steepness from the elongation; and a procedure for estimating the wave height from the steepness and the wave pitch. This is a method for measuring a target shape.

  The present invention is the first to enable continuous shape measurement of a high-speed moving object to which height fluctuation has been added, which has been difficult until now, with a simple imaging means. For example, in the online shape measurement in the steel industry, it is possible to measure the entire length of the entire surface, which is much higher density than the conventional method, improving the accuracy of building the product size and shape by operator guidance, and ensuring the complete quality for the user. It can be realized. In terms of cost, this method can be realized with a simple device. For example, it can be installed with much lower capital investment than a method in which a large number of laser displacement meters used in hot rolling are arranged. is there.

  In the following, the present invention will be described together with the operation with reference to the drawings. FIG. 1 shows an outline of the overall configuration of the optical shape measuring apparatus of the present invention. Reference numeral 1 denotes a steel plate that moves in the longitudinal direction as a measurement target (strip-shaped body), and has a shape defect such as an ear wave or a middle elongation therein. Reference numeral 2 denotes a linear laser light source. When a beam 3 radiated from the fan is irradiated onto a steel plate as a measurement target, a light cut image 4 is formed along the surface shape of the measurement target. Reference numeral 5 denotes a special camera having a successive integration type linear sensor, the function of which will be described in detail later. Reference numeral 6 denotes a measurement roll for measuring the conveyance speed of the measurement object, and reference numeral 7 denotes a rotational speed measuring device. Reference numeral 8 denotes a signal processing control device, which calculates the moving distance of the target object from the rotational speed signal of the rotational speed measuring device 7 and causes the linear laser light source 2 to emit light at a predetermined distance and simultaneously send it to the special camera 5. A predetermined video signal is obtained by controlling the clock. This signal is processed at high speed to continuously obtain shape index values. Reference numeral 9 denotes a measurement result display device.

First, the special camera 5 will be described. FIG. 2 is a diagram for explaining the function of the special camera and the structure of signal processing. Reference numeral 10 denotes a photoelectric conversion charge integration transfer unit in the two-dimensional semiconductor image pickup device in the light receiving unit of the camera. The two-dimensionally arranged photoelectric conversion elements have a vertical charge transfer section for each column, and receive and integrate charges from the respective photoelectric conversion elements in the middle of the transfer. Reference numeral 11 denotes a horizontal transfer reading unit whose output has the same form as a normal linear array.
Normally, when this type of sensor synchronizes the speed at which the real image to be imaged moves vertically on the photoelectric conversion surface and the transfer speed in the vertical direction, it means that the exposure is equivalently long, and the sensitivity and S / N ratio are reduced. Because it can be improved dramatically, it is used for ultra-high-speed shooting and low-light shooting.

  However, in the present invention, as disclosed in Patent Document 2, the above element is used in a completely different form. That is, it is not necessary to synchronize the target object and the vertical transfer speed, and transfer is performed as fast as necessary. When the laser is instantaneously emitted at an appropriate interval during this period, electric charges are accumulated at the position corresponding to the light section image. If the entire device is placed in a dark room or an interference filter that passes only laser light is placed in front of the camera lens, no charge is generated in the part that is not hit by the laser. This is a method that enables a much faster measurement than when using a simple television camera so far, in which the interval between the cut images can be narrowed, and a light cut image can be obtained continuously and continuously.

  Next, an example of the real-time signal processing method will be described. This signal processing is for real-time processing using the fact that the interval change of the light section image is proportional to the shape change. In FIG. 2, a preamplifier 12 amplifies the output of the sensor and simultaneously converts the impedance. A comparator 13 binarizes the analog signal and becomes 1 if there is a light section image. A shift register 14 is delayed by one line by a horizontal transfer clock. A latch 15 holds the current value and the previous value. Reference numeral 16 denotes a determiner, which outputs 1 only when the combination of the current value and the previous value is (1, 0), and determines that the next light section image has arrived in that column. Reference numeral 18 denotes an interval integration count value holding shift register, and reference numeral 17 denotes a first control circuit. While the output of the determiner 16 is 0, the first control circuit 17 simply increments the corresponding column register by +1. When it becomes 1, the value is incremented by 1 and the value is sent to the second control circuit 19. 21 is a reference interval value setter, and 20 is a change integration register. When the object to be measured is flat, the reference interval value is a straight line of equal intervals and holds the interval value. The second control circuit 19 subtracts the reference value from the current interval value from the first control circuit 17 to obtain the change amount, and adds it to the value of the 20 change integral value shift register. Therefore, each data of this register represents the current height in the width direction of the measurement object, and it is also possible to display a shape that changes every moment in real time. 22 is a D / A converter and 23 is a display.

以上が線状レーザ光源２と特殊カメラ５を用いて形状を測定する方法についての説明である。 FIG. 3 is a sectional view in the width direction obtained using the linear laser light source 2 and the special camera 5 when the reflector 24 is in the vicinity of the steel plate 1. When the steel plate is flat and does not show its original shape such as medium elongation or ear waves, the cross-section curve becomes a straight line when there is no vibration. Therefore, the displacement from the straight line of the cross-section curve is called the height of the steel plate here. .
4A and 4B are a side view of the optical arrangement of the present invention shown in FIG. 1 as viewed from the longitudinal direction and an enlarged view of the periphery of the plate edge. When the reflector 24 is present around the steel plate 1, depending on the thickness of the plate, the image of the laser beam reflected on the reflector and the steel plate is continuously connected, making it difficult to detect the plate edge. Therefore, it is desirable to adopt an optical arrangement that creates a shadow between the steel plate and the reflector as shown in FIG. 4 represents a laser beam when the laser 2 looks at the steel plate 1, and 25 indicates a field of view when the special camera 5 looks at the steel plate 1. If in FIG. 4 prospective angle theta _C from directly above the steel plate of the camera is small, the width of the shadow is Dtanshita _L determined by the yaw angle theta _L of the distance D and the laser from the steel sheet surface to the reflector. Since the camera's expected angle θ _C is actually finite, the shadow width is D (tanθ _L −tanθ _C ). To create a shadow that can be detected by the camera, the shadow width is larger than the width Δw corresponding to the camera resolution. To do. That is, the setting may be made as shown in equation (9).

This completes the description of the method for measuring the shape using the linear laser light source 2 and the special camera 5.

(First embodiment)
Next, a method for measuring the shape when there is vibration of the steel plate will be described. FIG. 5 (a) is a diagram showing a state in which vibration is applied to the medium elongation in which the vicinity of the center in the width direction of the steel sheet is elongated and the unevenness appears. When the position coordinate or time in the longitudinal direction is represented by t, the wave curve of the original shape at the width direction position x is f (x, t), and the substantially uniform vibration in the width direction is g (t), the steel plate The height h (x, t) of the steel plate when the vibration is applied is expressed by the equation (10).

したがって幅方向位置xにおける本来の形状f(x, t)は（10）式と（11）式から（12）式のように求められ、振動を除いた形状を検出することができる。

As will be described later, in the steel sheet production line, shapes such as intermediate stretch and ear waves appear at specific positions in the width direction, and therefore there exists a point x _m where the original shape wave does not appear in the width direction. Only the vibration g (t) should appear at the position x _m in the width direction. If the vibration is uniform in the width direction, the height of the steel plate at the position x _m is approximated as shown in equation (11). h (x _m , t) is equal to the vibration g (t).

Therefore, the original shape f (x, t) at the position x in the width direction is obtained as in Equation (12) from Equations (10) and (11), and the shape excluding vibration can be detected.

図５（ｂ）は中伸びの場合にこのようにして計算した長手断面曲線の長さL(x)である。鋼板の中央部では幅方向にほぼ一様な振動g(t)に中伸びによる波f(x, t)が加わるため、鋼板の高さh(x, t)の変動量、すなわち長手断面曲線の長さL(x)が大きくなり、振動のみが現れる幅方向位置においてはL(x)は小さくなる。したがってL(x)を計算し、L(x)が最小になる点を探索すれば本来の形状が現れていない幅方向位置x_mが求められる。 In order to obtain the point x _m where only the vibration appears, the longitudinal cross-section curve of h (x, t) is used as an amount representing the fluctuation in the longitudinal direction of the height h (x, t) of the steel plate at the position x in the width direction. The length L (x) is defined by equation (13). Here, as shown in FIG. 6, t _i represents an end point in the measurement section i divided in the longitudinal direction in order to calculate the length of the longitudinal section curve, and the subscript N represents the total number of sections.

FIG. 5B shows the length L (x) of the longitudinal section curve calculated in this way in the case of medium elongation. At the center of the steel sheet, the wave f (x, t) due to medium elongation is added to the vibration g (t) that is almost uniform in the width direction, so the fluctuation amount of the height h (x, t) of the steel sheet, that is, the longitudinal section curve The length L (x) increases, and L (x) decreases at the position in the width direction where only vibration appears. Therefore to calculate the L (x), L (x ) is not the original shape appear if searching for a point where the minimum width direction position x _m is obtained.

FIG. 6 shows a procedure for removing vibration when there is substantially uniform vibration in the width direction described above. First, the length L (x) of the longitudinal sectional curve including vibration at the position x in the width direction is calculated (S101). Then find the minimum x _m of L (x) with respect to the width direction (S102). The height h (x _m, t) of the steel sheet in the width direction position x from the steel plate at the minimum position x _m height h (x _m, t) subtracting (S103). After removing substantially uniform vibration in the width direction as described above, parameters representing flatness such as wave height, pitch, steepness, elongation, etc. may be calculated (S104). When a plurality of wave peaks and valleys are found, the wave height, pitch, and steepness may be obtained from these pairs, and the maximum value or average value among them may be extracted.
FIG. 10 shows an example in which the influence of vibration is removed by the above method. (A1) is a medium-stretched image before vibration removal, and the unevenness is shown in 256 gradations, and the concave portion is expressed as black and the convex portion is expressed as white. (A2) is a graph showing a longitudinal section near the center, left side and right edge of the middle stretched image of (a1). It seems that there is a wave near the edge in spite of medium elongation, and it is thought that it is affected by vibration. (B1) and (b2) show an image and a longitudinal section of the medium elongation after removing the vibration by the method of the first invention, but the waves due to the influence of the vibration near the edge could be eliminated.

第１の実施の形態にしたがって振動の影響を除去した後（14）式の伸び率を計算した場合、L(x_m)は図15における測定範囲の長さL₀=t_N−t₀となる。
張力変動が激しく平坦度の定量化が難しいラインにおいて、オペレータへのガイダンスとして伸び率を表示し、中伸びが出ているか否かの判断を行う目的に本発明の方法を適用するのであれば、第１の実施の形態で振動の影響を除去せずに伸び率を計算してもよい。
さらに波のピッチは図７のようにしても求められる。まず長手位置tにおいて幅方向位置xの断面曲線F(x, t)の長さC(t)は、前記L(x)を計算したときのように曲線を有限のM個の線分区間に分けて（15）式のようにして求める。

(Second Embodiment)
Next, calculation of the index of the shape of the strip will be described.
The curve h (x, t at the width direction position x with reference to the length L (x _m ) of the longitudinal sectional curve h (x _m , t) at the point x _m where L (x) is minimum ) Is calculated according to equation (14).

When the elongation of equation (14) is calculated after removing the influence of vibration in accordance with the first embodiment, L (x _m ) is the length of the measurement range L ₀ = t _N −t ₀ in FIG. Become.
In a line where tension fluctuation is large and flatness is difficult to quantify, if the method of the present invention is applied for the purpose of displaying whether the elongation is displayed as guidance to the operator and determining whether medium elongation has occurred, The elongation may be calculated without removing the influence of vibration in the first embodiment.
Further, the wave pitch can also be obtained as shown in FIG. First, at the longitudinal position t, the length C (t) of the cross-sectional curve F (x, t) at the width direction position x is calculated by dividing the curve into a finite number of M line segments as when L (x) is calculated. Divide it as shown in equation (15).

The length C (t) of the section curve F (x, t) is long at the top of the wave and short at the node when viewed in the longitudinal direction. Therefore, it is possible to obtain twice the period of C (t) as the wave pitch. When it is desired to detect not only the middle extension appearing in the center in the width direction but also the ear waves and the second extension appearing on both sides in the width direction, for example, sections DS, DQ, C, You may obtain | require a pitch from the change of each width direction cross-section curve in WQ and WS. In order to obtain the conventional wave pitch, it is necessary to make the time window long enough so that one period of the wave enters, but in this method, it is only necessary to set a half time window and the length of the cross-sectional curve in the width direction. Since the pitch is obtained only from the change in length, there is no need to perform a process for removing the influence of vibration in the longitudinal direction as in the first invention. FIG. 12 shows an example of medium elongation with a large pitch. (a) is a medium-stretched image, and the measurement range is only half the pitch, but looking at the change in the longitudinal direction of the light cutting curve in (b), two peaks appear, so the distance between the peaks And the original wave pitch can be calculated by multiplying by two.
If the elongation rate and the wave pitch can be calculated as described above, the steepness λ is obtained from the elongation rate ε using the sine wave approximation (8), and the wave pitch P is multiplied by the steepness λ by the wave pitch P. Can be obtained approximately.

FIG. 9 summarizes the process of claim 3 as a flow. First, in each position x in the width direction of the steel sheet to calculate the length of the longitudinal cross section curves L (x) (S201), obtains the width-direction position x _m giving the minimum value of L (x) (S202), (14) The elongation percentage is calculated according to the formula (S203). Next, the length C (t) of the light cutting curve at the longitudinal position (or time t) is calculated according to the equation (15) (S204), and the pitch P is calculated from the interval between the vertices (mountain or valley) of C (t). Is obtained (S205). The steepness λ is calculated from the elongation ε using the conversion formula (8) of the steepness and elongation in the sine wave approximation (S206), and the wave height H is obtained by multiplying the steepness λ by the pitch P (S207). .

FIG. 11 shows an example in which the elongation rate is calculated for medium elongation, ear wave, and second elongation. All of them capture the characteristics of the shape well, and you can see at a glance what the shape is by looking at the elongation graph. Unlike the method of arranging a large number of laser displacement meters in the width direction, the shape can be expressed with high density.
The advantage of using the elongation rate is that, firstly, the type of shape such as medium elongation, ear wave, and the second elongation appearing at a point in the width direction can be clearly distinguished by the elongation curve. Now, when finding the pitch, it is necessary to set the time window to a certain length so that one period of the wave enters, but in the case of the elongation rate, it can be calculated without one period. In the case of a plate, even if a deformation such as a bend occurs in the steel plate in the middle of measurement, an error that occurs when searching for vertices as in finding the wave height and pitch does not occur. When the on-site operator of the production line changes the mill reduction state while checking the shape of the exit side of the temper rolling mill, the elongation curve in FIG. 6 is very useful as operator guidance.
In the above, the shape measuring method when the measurement object is a belt-like body such as a steel plate has been described. However, the present invention can also be applied to flatness measurement or shape disturbance measurement of an object having a continuous surface such as a tubular body of a pipe. For example, in order to measure the shape of the pipe circumferential direction with respect to the pipe, the pipe axis direction may be taken as the width direction and the pipe circumferential direction taken as the longitudinal direction. In order to measure the shape in the tube axis direction, the tube circumferential direction may be measured in the width direction and the tube axis direction in the longitudinal direction.

It is a figure which shows the whole structure of this invention. It is a figure which shows the function of a special camera, and the structure of signal processing. It is a figure showing the linear laser beam imaged with the special camera when there exists a reflector around a steel plate. It is the figure explaining the optical arrangement | positioning for detecting a plate edge reliably, when there exists a reflector around a steel plate. It is a figure explaining the process of removing a vibration by deducting the height fluctuation | variation of the position containing only a vibration component from the middle stretched shape containing a vibration. It is a figure explaining the process of removing the influence of the vibration of a strip. It is a figure explaining the relationship between the longitudinal direction change of the length of a light cutting curve, and a pitch. It is a figure explaining the method of dividing | segmenting the width direction of a steel plate and calculating | requiring a pitch from the longitudinal direction change of the length of the optical cutting curve in each area. It is a figure explaining the procedure which calculates | requires an elongation rate and a pitch, and calculates steepness and a wave height by sine wave approximation. It is a figure explaining the Example which removed the vibration. It is a figure explaining the Example which removed the vibration. It is a figure explaining the example which calculated the elongation rate of middle elongation. It is a figure explaining the example which calculated the elongation rate of the ear wave. It is a figure explaining the example which calculated the elongation rate of the 2nd elongation. It is a figure explaining that a pitch is calculated | required from the change of the length of a light cutting curve about the medium elongation with a large wave pitch. It is a figure explaining the shape made into a measuring object by the present invention. It is a figure explaining the definition of the wave height which is the parameter | index of flatness, a wave pitch, and steepness. It is a figure explaining the method of calculating the length of a longitudinal section curve. It is a figure which shows the relationship between a curve, a wave height, and a pitch when a wave shape is assumed to be a sine wave.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Measuring object 2 Linear laser light source 3 Linear laser beam 4 Optical cut image 5 Special camera 6 Speed measurement roll 7 Rotational speed measuring device 8 Signal processing control board 9 Display apparatus 10 Photoelectric conversion charge integration transfer part 11 Horizontal transfer reading Stocking unit 12 Preamplifier 13 Comparator 14 Shift register 15 Latch 16 Determinator 17 First control circuit 18 Shift register 19 for holding interval accumulated count value Second control circuit 20 Shift register 21 for integration of change Reference interval value setting unit 22 D / A converter 23 Display 24 Reflector 25 Field of view 3 'of steel plate 1 Laser line of steel plate 1

Claims (3)

Using a linear laser light source whose output is modulated, a linear laser beam is projected on the strip in the width direction of the strip to form a light cutting curve (image). It is a shape measuring method of a light cutting method for reconstructing the shape of the band-shaped body by performing overlapping imaging using a delay integration type linear sensor while shifting by a predetermined interval on the band-shaped body,
A point in the width direction of the belt-like body that minimizes the height variation along the longitudinal direction of the belt-like body is obtained, and the height variation in the longitudinal direction at the point is defined as the magnitude of the vibration of the belt-like body. A method for measuring an optical shape, comprising: measuring an index of the shape of the belt-like body over the entire surface or a part of the belt-like body by subtracting from the height measured at each point.   The shape index is any one or all of a wave height, a wave pitch, a steepness, and an elongation rate, where a change in the position of the shape of the belt-like body is referred to as a wave. Optical shape measurement method. A procedure for calculating the length of the longitudinal section curve at a plurality of discrete points x in the width direction of the strip, and a procedure for searching for a point x _{m in the} width direction where the length of the longitudinal section curve is minimum When,
A procedure for calculating the elongation at each point x in the width direction based on the length of the longitudinal section curve at the point x _m ;
Calculating the length of the light cutting curve on the strip surface at a plurality of discrete points t in the longitudinal direction;
Calculating the wave pitch from the apex (crest or trough) spacing in the longitudinal change in the length of the light cutting curve;
A procedure for calculating the steepness from the elongation;
The optical shape measuring method according to claim 2, further comprising a step of estimating a wave height from the steepness and the wave pitch.

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