JP5599335B2 - Thickness measuring device - Google Patents

Description

  The present invention relates to a thickness measuring device that measures the thickness of a steel plate or the like being conveyed using a distance detector using a laser beam.

  As a thickness measuring device for shapes of various materials such as steel plates and products, a device using a distance detector by a laser beam is widely used. This apparatus can automatically and continuously measure the thickness of the material to be measured being conveyed.

  In addition, special safety management like a thickness meter using γ-rays is not required, and furthermore, since the beam diameter is smaller than the beam diameter of radiation, changes in thickness can be measured with high resolution. is there. Therefore, practical application is also progressing in the field where it is desired to accurately measure a sudden shape change in the vicinity of the end of the measurement object.

  An example of this configuration is shown in FIG. In the figure, reference numerals 1 and 2 denote distance detection based on the principle of triangulation using laser transmitters 1a and 2a placed on the upper and lower sides of the C-shaped frame 3 with the measurement object 7 in between. The distance La between the distance detector 1 and the measurement object 7 and the distance Lb between the distance detector 2 and the measurement object 7 are respectively obtained by the measuring device, and each distance detector 1 is sent to the thickness calculator 25. 2 is set in advance, and the thickness t of the measuring object 7 is calculated from the set distance L and the obtained distances La and Lb as t = L−La−Lb. And a thickness calculator 25 to be obtained.

  Each of the distance detectors 1 and 2 includes laser oscillators 1a and 2a, light receivers 1b and 2b including a position sensor such as a CCD camera (not shown), and a distance calculator (not shown).

  Among the applications of such a thickness measuring apparatus is, for example, the thickness measurement of a large-shaped steel plate such as a thick plate. In the case of a C-shaped frame having a long arm, there is a problem that the set distance L drifts due to a change in ambient temperature.

  In order to eliminate this drift, a mechanical calibration device is disclosed in which the calibration reference sample is set at a high speed in the space of the C-shaped frame by using the idle time between the measurement intervals of the steel plate ( For example, see Patent Document 1.)

Japanese Patent No. 3880909 (FIG. 1, page 1)

  Since the method disclosed in Patent Document 1 has a mechanical structure, the time required for calibration requires at least several seconds. Therefore, there is a problem that calibration cannot be performed when the idle time is less than this.

  The present invention has been made to solve the above problems, and without using a mechanical calibration device, the displacement of the distance between the distance detectors due to the mechanical drift of the C-shaped frame is instantaneously measured. An object of the present invention is to provide a thickness measuring device that corrects a thickness measurement error.

In order to achieve the above object, the thickness measuring apparatus according to the embodiment is disposed on the upper and lower arms of the C-shaped frame sandwiching the measurement object, and is perpendicular to the surface of the measurement object. The first distance detector for irradiating the first laser beam to obtain the distance to the object to be measured and the lower part of the upper and lower arms of the C-shaped frame sandwiching the object to be measured. , A second distance detector for irradiating the back surface of the measurement object with a second laser beam from a vertical direction to obtain a distance from the measurement object; an output of the first distance detector; A thickness calculating unit that obtains a thickness from the output of the second distance detector, provided at a lower portion of the arm part, and in the C-shaped frame arm part space, the measurement unit During a period in which no object is present, the first laser beam And a half mirror provided on the road, the a first beam position displacement detector for detecting a change in position of the reflected first laser beam of the half mirror, the output of the first beam position displacement detector A first beam position displacement processing unit for obtaining a displacement of an incident angle of the first laser beam and a displacement of a distance between the distance detectors between the first distance detector and the second distance detector; The first beam position displacement detector is provided in the optical path of the laser beam, and is reflected by the first half mirror that deflects the optical path of the laser beam in the horizontal direction and the first half mirror. A second half mirror provided in parallel with the first half mirror for transmitting and reflecting the laser beam, and a first position sensor for detecting the position of the laser beam transmitted through the second half mirror. And a second position sensor that detects a position of the laser beam reflected from the second half mirror, and an optical path length between the first half mirror and the first position sensor; The optical path length between the first half mirror and the second position sensor is set to a different value, and the first beam position displacement processing unit is configured to use the first position sensor and the second position sensor. A displacement of the incident angle and a displacement of the distance between the distance detectors are obtained from a displacement of the first laser beam position detected by a position sensor, and the obtained displacement of the incident angle and the distance detector are obtained. The thickness measurement value obtained by the thickness measurement unit is automatically corrected based on the displacement of the distance between them.

  According to the thickness measuring apparatus having the above configuration, a mechanical calibration device is not used, and the displacement of the distance between the distance detectors due to the mechanical drift of the C-shaped frame is instantaneously measured to correct the thickness measurement error. A thickness measuring device can be provided.

1 is a configuration diagram of a thickness measuring apparatus according to Embodiment 1. FIG. FIG. 3 is an optical setting diagram for explaining the measurement principle of the thickness measuring apparatus according to the first embodiment. The block diagram of the thickness measuring apparatus of Example 2. FIG. FIG. 5 is an optical setting diagram for explaining the measurement principle of the thickness measuring apparatus according to the second embodiment. The block diagram of the thickness measuring apparatus of Example 3. FIG. FIG. 5 is an optical setting diagram for explaining the measurement principle of the thickness measuring apparatus according to the third embodiment. The block diagram of the conventional thickness measuring apparatus.

  Embodiments of the present invention will be described below with reference to the drawings.

  With reference to FIG.1 and FIG.2, the thickness measuring apparatus 100 of Example 1 is demonstrated. FIG. 1 shows a configuration diagram of the first embodiment, and FIG. 2 shows an optical dimension diagram set in the configuration of FIG.

  Focusing on the fact that the displacement of the beam position of the first distance detector 1 above the arm part of the C-shaped frame 3 is large, the principle of this correction is the second distance detector 2 below the arm part with little displacement. A position sensor for detecting the first laser beam displacement is provided on the optical substrate, and a minute displacement is detected, and the displacement detected by the thickness calculator 20 is corrected.

  A thickness measurement apparatus 100 shown in FIG. 1 includes a detection unit 10 and a thickness calculation unit 20. The detection unit 10 is disposed on the upper and lower arms of the C-shaped frame 3 sandwiching the measurement object 7, and is perpendicular to the surface of the measurement object 7 from the laser transmitter 1 a to the first. A first distance detector 1 for obtaining a distance from the measurement object 7 by irradiating a laser beam; and a lower part of the upper and lower arms of the C-shaped frame 3 sandwiching the measurement object 7, A second distance detector 2 is provided that irradiates the second laser beam from the laser transmitter 2a in a direction perpendicular to the back surface of the measurement object 7 to obtain the distance to the measurement object 7.

  Furthermore, a half mirror is provided in the optical path of the first laser beam in a period in which the measurement object 7 does not exist in the arm space of the C-shaped frame 3 provided at the lower part of the arm, and the reflection of the half mirror A first beam position displacement detector 4a for detecting a change in the position of the one first laser beam, a displacement of the incident angle of the first laser beam from the output of the first beam position detector 4a, A first beam position displacement processing unit 4b that obtains a displacement of the distance between the distance detectors 1 between the first distance detector 1 and the second distance detector 2;

  The thickness calculator 20 obtains the thickness from the output of the first distance detector 1 and the output of the second distance detector 2, and further calculates the displacement of the obtained incident angle and the distance between the distance detectors. The obtained thickness measurement value is corrected based on the displacement of the distance.

  Next, details of the first beam position displacement detector 4a and the first beam position displacement processing unit 4b will be described. The first beam position displacement detector 4a is provided in the optical path of the first laser beam irradiated in the x-axis direction, and deflects the optical path of the first laser beam in the horizontal direction on the left side of the y-axis. A half mirror M1 and a second half mirror M2 that transmits and reflects the first laser beam reflected by the first half mirror M1 and is provided in parallel with the first half mirror M1 are provided.

  Furthermore, a first position sensor D1 that detects the position of the first laser beam that has passed through the second half mirror M2, and a second that detects the position of the first laser beam that has reflected from the second half mirror M2. Position sensor D2.

  At this time, the optical path length b between the first half mirror M1 and the first position sensor D1 and the optical path length (c + d) between the first half mirror M1 and the second position sensor are set to different positions. Set.

  The optical system of the thickness measuring apparatus 100 set in this way is shown in FIG. FIG. 2 shows that the first laser beam irradiated in the x-axis direction from the point P0 decreases the displacement m of the optical path length (distance between the distance detectors) in the x-axis direction (optical axis direction), and the y-axis direction. The figure shows a case where the optical axis drifts to a position rotated by a small angle ∠θ around the point P1.

In this case, the first position sensor D1 and the second position sensor D2 measure the displacements Y1 and Y2, respectively. This displacement is
Y1 = n + tan θ · (a + b) −m · tan θ (1)
Y2 = n + tan θ · (a + c + d) −m · tan θ (2)
Value.

Therefore, the beam position displacement processing unit 4b obtains the displacement angle θ of the incident angle of the laser beam by the following equation.
∠θ = tan ⁻¹ (Y2−Y1) / (c + d−b) (3)
The thickness calculator 20 obtains a corrected thickness t from the following equation with respect to the thickness t0 before correction.
t = t0−L (1 / cos θ−1) (4)
Although m can also be obtained from the above equations (1) and (2), in general, m can be ignored in the configuration of the thickness measuring apparatus 100 because m << a, m << b, and m << c.

  That is, the first beam position displacement processing unit 4a detects the incident angle displacement ∠θ and the distance detection from the beam position displacements (Y1, Y2) detected by the first position sensor D1 and the second position sensor D2. The displacement m of the distance between the instruments can be obtained instantaneously by calculation without requiring a mechanical setting time.

  In the description of the present embodiment, the displacement of the beam position has been described as the displacement in the xy plane parallel to the paper surface as shown in FIG. 1, but if there is a displacement in the direction orthogonal to the paper surface, It goes without saying that the three-dimensional displacement can be corrected by using the sensor D1 and the position sensor D2 as a two-dimensional position sensor.

  A second embodiment will be described with reference to FIGS. The difference between the second embodiment and the first embodiment is that the displacement m of the distance between the distance detectors is negligible in the first embodiment and can be ignored. However, the second embodiment is different from the distance between the distance detectors. The displacement m is determined so that this value is measured with high resolution.

  As shown in FIG. 3, in the configuration shown in the first embodiment, the measurement object 7 is provided in the upper part of the arm portion of the C-shaped frame 3 and the measurement object 7 does not exist in the arm space of the C-shaped frame 3. , Provided in the optical path of the first laser beam, provided with a pair of half mirrors (M3, M4) for setting the first laser beam at different incident angles, and provided at the lower part of the arm part, which are different And a third position sensor D3 for detecting the position of the laser beam irradiated at the incident angle, and based on the output of the third position sensor D3, the second beam position displacement processing unit 4b uses a distance between the distance detectors. The displacement of the distance m is obtained.

  The third position sensor can be provided on a base different from the base of the distance detector 2, but is preferably provided on the same base.

  FIG. 4 shows the optical system of the first laser beam in the configuration of FIG. The pair of third and fourth half mirrors M3 and M4 deflect the first laser beam to an incident angle ∠θ2. In the output D3 of the third position sensor, the displacement (Y3-Y0) in this case can be expanded so that the displacement can be measured with high resolution. It can be measured.

In the beam position displacement processing unit 4b, m can be obtained from the following equation (5).
m = (Y3-Y0) · sin θ2 (5)

  Embodiment 3 will be described with reference to FIGS. 5 and 6. Example 3 differs from Example 1 in Example 1. In Example 1, two position sensors are provided at two different optical path lengths, and the displacement 入射 θ of the incident angle and the distance detection are detected from the displacement of the two beam positions. Although the displacement m of the distance between the instruments is obtained by calculation, in the third embodiment, a pair of half mirrors M5 and M6 are provided in the optical path of the first laser beam, and signals with different optical path lengths are sent to one position sensor. This is because the configuration is simplified.

  Specifically, the first beam position displacement detector D1 is provided in the optical path of the first laser beam and reflected by the first half mirror M1 that deflects the optical path in the horizontal direction and the first half mirror M1. Fifth and sixth half mirrors (M5 and M6) that transmit the first laser beam and are provided in parallel with the first half mirror and at a preset distance f, and third and fourth half A first position sensor D1 for detecting the position of the first laser beam that has passed through the mirrors (M5, M6) is provided, and the position signals of different optical path lengths are simultaneously detected by one first position sensor D1.

  The first beam position displacement processing unit 4b is to obtain the displacement of the incident angle from the displacement of the two beam positions detected by the first position sensor.

  The optical system configured as described above is shown in FIG. As shown in this figure, the output Y2 of the reduced first laser beam detected at different positions can be obtained by the following equation (6).

Y2 = n + tan θ (a + b + 2f) −m · tan θ (6)
Although the output of Y2 in the first position sensor D1 is attenuated between the half mirrors as compared with the output of Y1, the output is reduced, but optimal detection is achieved by appropriately adjusting the power of the first laser beam. It is possible.

  In addition, although some embodiment of this invention was described, these embodiment is shown as an example and is not intending limiting the range of invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the scope equivalent to the invention described in the claims.

DESCRIPTION OF SYMBOLS 1, 2 Distance detector 1a, 2a Laser transmitter 1b, 2b Light receiver 3 C-shaped frame 4a 1st beam displacement detector 4b Beam position displacement process part 4c Beam deflection | deviation part 4d 2nd beam displacement detector 7 Measurement object Object 10, 15 Detector 20, 25 Thickness calculator 100 Thickness measuring device M1, M2, M3, M4 Half mirror D1, D2, D3, D4, Position sensor

Claims (3)

Located on the upper and lower arms of the C-shaped frame sandwiching the measurement object, the first laser beam is irradiated from the vertical direction to the surface of the measurement object, and the distance from the measurement object A first distance detector for determining
The measurement object is disposed below the upper and lower arms of the C-shaped frame sandwiching the measurement object, and irradiated with a second laser beam from the vertical direction on the back surface of the measurement object. A second distance detector for determining the distance of
A thickness calculator for obtaining a thickness from the output of the first distance detector and the output of the second distance detector;
A thickness measuring device comprising:
A half mirror is provided in the optical path of the first laser beam and reflected by the half mirror during a period in which the measurement object does not exist in the C-shaped frame arm space provided at a lower portion of the arm portion. A first beam position displacement detector for detecting a change in the position of the first laser beam;
The displacement of the incident angle of the first laser beam from the output of the first beam position displacement detector, and the displacement of the distance between the distance detectors between the first distance detector and the second distance detector. A first beam position displacement processing unit for obtaining
With
The first beam position displacement detector is provided in an optical path of the laser beam, and a first half mirror that deflects the optical path of the laser beam in a horizontal direction;
A second half mirror provided in parallel with the first half mirror for transmitting and reflecting the laser beam reflected by the first half mirror;
A first position sensor that detects a position of the laser beam that has passed through the second half mirror; a second position sensor that detects a position of the laser beam that has reflected from the second half mirror;
With
The optical path length between the first half mirror and the first position sensor and the optical path length between the first half mirror and the second position sensor are set to different values,
The first beam position displacement processing unit is configured to detect a displacement of the incident angle and a distance between the distance detectors based on the displacement of the first laser beam position detected by the first position sensor and the second position sensor. And the displacement of the distance of
A displacement of the angle of incidence determined, based on the displacement of the distance between the distance detector, thickness, characterized in that to automatically correct the thickness measurements obtained in the thickness measuring unit Measuring device. Further, beam deflection is provided with a pair of third and fourth half mirrors provided on an upper portion of the arm portion, provided in an optical path of the first laser beam, and setting the first laser beam at different incident angles. And
A third position sensor provided at a lower portion of the arm portion for detecting a position of the first laser beam irradiated at a different incident angle;
With
The thickness measuring apparatus according to claim 1, further comprising: a second beam position displacement processing unit that obtains a displacement of a distance between the distance detectors based on an output of the third position sensor. The first beam position displacement detector is provided in an optical path of the laser beam, and a first half mirror that deflects the optical path of the laser beam in a horizontal direction;
Fifth and sixth half mirrors provided at a preset distance in parallel with the first half mirror that transmits the laser beam reflected by the first half mirror;
A first position sensor for detecting a position of the laser beam transmitted through the fifth and sixth half mirrors;
With
The first position sensor transmits the laser beam transmitted through the fifth and sixth half mirrors, transmits the fifth half mirror, reflects the surface of the sixth half mirror, and further And the laser beam reflected on the back surface of the half mirror of 5 and transmitted through the sixth half mirror,
The thickness measuring apparatus according to claim 1, wherein the first beam position displacement processing unit obtains a displacement of the incident angle from displacements of two different beam positions detected by the first position sensor.

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