JP6412735B2 - Thickness measuring device using optical distance detector - Google Patents

Description

  Embodiments described herein relate generally to a thickness measuring apparatus using an optical distance detector.

  2. Description of the Related Art Conventionally, in a steel plate production line, a thickness measuring device using an optical distance detector is known as a device for measuring the thickness of a conveyed steel plate.

  A thickness measuring apparatus using such an optical distance detector has a pair of optical systems that irradiate light on both sides of the object to be measured and receive the reflected light to detect displacement from the reference position. There is a thickness measuring device that includes a displacement sensor (distance detector) and a scanning mechanism that moves the distance detector with respect to the object to be measured, and measures the thickness distribution of the object to be measured (for example, Patent Documents). 1).

  In the case of measuring the thickness of a steel plate or the like, there is a thickness measuring device in which an optical distance detector is provided facing an arm portion of a C-shaped frame (see, for example, Patent Document 2).

  In general, in a thickness measuring apparatus provided with an optical distance detector, various devices have been devised in order to control the distance between a pair of optical distance detectors and a reference position to be constant.

  For example, in the optical thickness measuring device disclosed in Patent Document 1, in order to suppress fluctuations in the distance between the reference positions due to bending or bending of the rail that moves the distance detector, the thickness at each position in the moving direction is previously determined. The thickness at the reference plate is measured, the deviation from the thickness reference plate is stored, and the measured value is corrected.

  In addition, in the thickness measurement device disclosed in Patent Document 2, in order to suppress the variation in the set distance between the distance detectors, a heat insulating material is lined on the inner surface of the C-type frame that houses the distance detector, The interior of the C-type frame is air-conditioned so that the temperature in the C-type frame is uniform.

JP-A-4-369409 JP 2009-128322 A

  The thickness measurement of a steel plate such as a thick plate is required to continuously measure a thickness distribution in the width direction at a preset position in the width direction of the steel plate.

  Further, when the object to be measured is a red-heated steel plate, the change pattern of the ambient temperature at which the apparatus is installed changes frequently depending on not only the change in the outside air temperature but also the state of the radiant heat of the steel plate.

  In the case of a thickness measuring device placed in such a temperature environment, in order to satisfy the required measurement accuracy, when a moving mechanism of a distance detector as disclosed in Patent Document 1 is applied, a reference is required. Reproducibility of the bending of the rail, which is a moving mechanism for setting the distance to the position, and the bending is necessary. In addition, as disclosed in Patent Document 2, it is necessary to insulate the measuring device against outside air temperature, radiant heat, and the like, and to air-condition the thickness measuring device to which the distance detector is fixed.

  However, with the method disclosed in Patent Document 1, it is difficult to learn and store the distance between the reference position for various temperature change patterns, and there is a problem that it takes time and effort.

  In addition, providing the air conditioning equipment disclosed in Patent Document 2 has a problem that the apparatus is large and complicated, and maintenance for maintaining a constant temperature environment is troublesome.

  The present invention is a thickness measuring apparatus using an optical distance detector, which detects the displacement of the distance from the reference position of the optical distance detector due to a change in external temperature, An object of the present invention is to provide a thickness measuring device using an optical distance detector capable of easily correcting a thickness measurement error.

  In order to achieve the above object, the thickness measuring apparatus using the optical distance detector according to the present embodiment is configured to measure a pair of optical distance detectors for obtaining a distance to the object to be measured. Provided in opposition to the vertical direction of the object, and determine the distance between the front and back surfaces of the object to be measured and the respective reference positions in the vertical direction of the optical distance detector set in advance. A thickness measuring device using an optical distance detector for determining the thickness of an object, the thickness measuring device using the optical distance detector comprising a detection unit and a control unit, the detection unit A portal frame that supports the optical distance detector in a vertical direction at a thickness measurement position in the width direction of the object to be measured across the object to be measured; and both ends of the portal frame The optical distance detector fixed to the support and provided on the surface side is the width direction of the object to be measured. An upper guide rail that moves to the thickness measurement position, and a lower guide rail that moves the optical distance detector provided on the back surface side to the thickness measurement position, with both ends fixed to the support of the portal frame. The optical distance detector on the surface side that is fixed to the upper guide rail, irradiates the surface of the object to be measured with a laser beam to obtain the distance from the position of the reflected light, and is fixed to the lower guide rail, The optical distance detector on the back surface side that irradiates the back surface of the object to be measured to obtain the distance from the position of the reflected light, and the optical base of the optical distance detector on the front surface side are fixed integrally. The laser beam projector is fixed to the left and right columns of the portal frame, and the laser beam emitted from the laser beam projector in the horizontal axis direction is received on a plane orthogonal to the laser beam. A pair of laser beam position detectors for detecting a light receiving position of the laser beam, and the control unit outputs the optical distance detector on the front surface side and the optical distance detector on the rear surface side, From the output of the pair of laser beam position detectors and the thickness calculator that obtains the distance from the preset reference position and obtains the thickness by referring to a thickness calibration table prepared in advance. The distance displacement between the optical distance detector on the surface side and the reference position and the distance displacement between the reference position due to the angular displacement with respect to the vertical direction are referred to a position calibration table calibrated in advance. The position calculating unit obtained by driving the upper and lower guide rails to move the optical distance detector on the front surface side and the optical distance detector on the rear surface side to the thickness measurement position. Measurement position control unit and front A thickness correction calculation unit that corrects a thickness output obtained by the thickness calculation unit with reference to a distance displacement with respect to a reference position of the optical distance detector obtained by the position calculation unit. Characterized by

The block diagram of the detection part of the thickness measuring apparatus of embodiment. The block diagram of the control part of the thickness measuring apparatus of embodiment. The block diagram of a laser beam projector. Explanatory drawing of a measurement error. Explanatory drawing of the measurement error at the time of bending generation | occurrence | production.

  Hereinafter, a thickness measuring apparatus using the optical distance detector of the present embodiment will be described with reference to the drawings.

  FIG. 1 is a configuration diagram of a detection unit 50 of a thickness measuring device (hereinafter referred to as a thickness measuring device) using the optical distance detector of the present embodiment.

  Fig.1 (a) is sectional drawing which looked at the to-be-measured object 30 conveyed on the conveyance table used as the conveyance reference plane PL (xy plane) in the y-axis direction from the front, FIG.1 (b) is FIG. It is the fragmentary sectional view seen from AA 'shown to Fig.1 (a).

  The thickness measuring apparatus 100 is provided with a pair of optical distance detectors 1T and 1B for obtaining a distance from the object to be measured 30 facing the vertical direction (z axis) of the object to be measured 30 moving in the horizontal direction. The thickness of the object to be measured 30 is obtained by determining the distance (dt, db) between the front and back surfaces of the object to be measured 30 and the respective reference positions Pt and Pb in the vertical direction of the optical distance detector set in advance. I ask for it.

  In FIG. 1, the thickness measuring apparatus 100 includes a detection unit 50 shown in FIG. 1 and a control unit 60 shown in FIG.

  The detection unit 50 straddles the measurement object 30 and opposes the optical distance detector 1T and the optical distance detector 1B in the vertical direction at the thickness measurement position in the width direction (x-axis direction) of the measurement object 30. The top frame frame 20 is supported by the top, and the optical distance detector 1T provided on the front surface side is fixed to the columns of the portal frame 20 and both ends are moved to the thickness measurement position in the width direction of the object to be measured. The guide rail 2T is provided with an optical distance detector 1B which is fixed to the support of the portal frame 20 at both ends and provided on the back surface side and which moves to the thickness measurement position.

  Further, it is fixed to the upper guide rail 2T, and is fixed to the surface side optical distance detector 1T for obtaining the distance from the position of the reflected light by irradiating the surface of the object 30 with a laser beam and the lower guide rail 2B. And an optical distance detector 1B on the back surface side for obtaining a distance from the position of the reflected light by irradiating the back surface of the object 30 with a laser beam.

  Further, the laser beam projector 4 fixed integrally with the optical base of the optical distance detector 1T on the surface side, and the left and right columns of the portal frame 20 are fixed to the horizontal axis (x axis) from the laser beam projector 4 A pair of laser beam position detectors 5R and 5L that receive a laser beam irradiated in a direction on a plane (yz plane) orthogonal to the laser beam and detect a light receiving position of the laser beam.

  Next, the configuration of the control unit 60 will be described with reference to FIG. The control unit 60 obtains a distance from a preset reference position (Pt, Pb) from the outputs of the optical distance detector 1T on the front surface side and the optical distance detector 1B on the rear surface side, The thickness calculator 11 that obtains the thickness with reference to the prepared thickness calibration table, and the reference position of the optical distance detector 1T on the surface side from the outputs of the pair of laser beam position detectors 5R and 5L. A position calculator 15 that obtains a distance displacement (Δdθ) between a distance displacement (Δd) between the reference position and a reference position by an angular displacement (θ) with respect to the vertical direction with reference to a position calibration table calibrated in advance; Is provided.

  Further, the thickness measurement position control for driving the upper and lower guide rails 2T and 2B to move the optical distance detector 1T on the front surface side and the optical distance detector 1B on the rear surface side to the thickness measurement position. And a thickness correction calculation unit 16 that corrects the thickness output obtained by the thickness calculation unit 11 with reference to the distance displacement (Δd, Δdθ) output obtained by the position calculation unit 15.

  Next, the structure of each part of the detection part 50 is demonstrated. Each of the optical distance detectors 1T and 1B includes a laser beam projecting part and a light receiving part on an optical substrate made of a single rigid body (not shown). A configuration is selected.

  Also, the laser beam projecting section and the light receiving section are provided on this optical base, and the light projecting angle and the light receiving angle are fixed. The optical substrates are fixed to the guide rails 2T and 2B of the ball screw, respectively, so that the thickness reference position in the vertical direction satisfies the required accuracy.

  The upper guide rail 2T and the lower guide rail 2B are each provided with a guide rail drive unit 3T and a guide rail drive unit 3B for driving the guide rail 2T, and the guide rail is supported at both ends thereof, and the thickness is measured. The position control unit 13 drives the guide rail to set the optical distance detectors 1T and 1B in synchronization with the thickness measurement position in the width direction required for each object to be measured 30.

  The guide rail driving unit 3T and the guide rail driving unit 3B are fixed to the left and right columns of the portal frame 20 as shown in FIG.

  Further, as shown in FIG. 3, the laser beam projector 4 provided integrally on the optical base of the optical distance detector 1T includes a laser beam collimator 4a and a laser beam splitter 4b, and the laser beam collimator 4a includes: One or two laser beams are generated from the vertical direction, the laser beam splitter 4b is a triangular prism mirror, and irradiates the laser beam in different directions on the horizontal axis (x axis).

  The position displacement detectors 5R and 5L for detecting the position of the laser beam are line scan type CCD cameras or area scan type CCD cameras, and are fixed to the left and right columns of the portal frame 20 and fixed to the upper guide rail. The displacement of the reference position of the optical base of the optical distance detector 1T fixed to 2T is detected.

  The portal frame 20 is required to have a material and structure so that the fixed position accuracy of the pair of position displacement detectors 5R and 5L for detecting the displacement satisfies the required accuracy for the reference measurement surface PL.

  In the case where the object to be measured 30 is a red-heated steel plate, the surroundings of the object to be measured 30 excluding the optical space between the detection unit 50 and the object to be measured 30 are covered with a heat insulating cover 22 and the gate shape is used. The periphery of the detection unit including the periphery of the frame is covered with a heat insulating cover 21 that insulates the outside air.

  Next, the configuration of each unit of the control unit 60 will be described. The thickness calculation unit 11 is configured to detect the distance dt between one reference position Pt of the distance detectors Ds set in advance from the optical distance detector 1T and the optical distance detector 1B and the DUT 30, and the other Each distance detection signal corresponding to the distance db between the reference position Pb and the object to be measured 30 is received, the distance is obtained by referring to a thickness calibration table prepared in advance, and further, the object to be measured 30 is measured. Is obtained by calculation (t = Ds− (dt + db)).

  Further, the thickness measurement position control unit 13 drives the upper guide rail drive unit 3T and the lower guide rail drive unit 3B to the measured object width Ws and the thickness measurement position Xrs (not shown) set in advance from the upper level. Then, the optical distance detector 1T and the optical distance detector 1B are moved to the set position. Then, the moved thickness measurement position xs (actual value) is transmitted to the position calculation unit 15.

  Next, the position calculator 15 receives the displacement (Δdr, Δdl) from the reference position Po of the optical distance detector 1T from the laser beam position detector 5R and the laser beam position detector 5L, and responds to this displacement. The displacement of the reference position (Pt) to be obtained is obtained with reference to a position calibration table created in advance. A method of obtaining displacements (Δd, Δdθ) from the reference position (Pt) corresponding to this displacement will be described later.

  Next, the thickness correction calculation unit 16 corrects the displacement (Δd, Δdθ) obtained by the position calculation unit 15 with respect to the thickness t of the measurement object 30 obtained by the thickness calculation unit 11 to be corrected. Output the thickness.

  The position calculation unit 15 and the thickness correction calculation unit 16 can be configured integrally with the thickness calculation unit 11.

  Next, the optical setting of the thickness measuring apparatus 100 configured as described above and how to obtain the displacement corresponding to the reference position of the optical distance detector 1T and the optical distance detector 2T will be described with reference to FIGS. This will be described with reference to FIG.

FIG. 4 is an optical setting diagram of the thickness measuring apparatus 100. The reference positions Pt and Pb between the optical distance detector 1T on the upper side of the object to be measured 30 and the lower optical distance detector 1B of the object to be measured 30 and the distance Ds therebetween, and the respective optical distance detectors 1T and 1B. Assuming distances dt and db from the reference position, the thickness calculator 11 calculates the thickness t of the device under test 30 based on the following calculation formula.
t = Ds− (dt + db) (1)

Here, if the reference position Po of the upper optical distance detector 1T is bent at the central portion in the length direction of the upper guide rail 2T and is displaced Δd to the point Pv, the thickness calculation unit 13 at that time The output t ′ is
t ′ = Ds− (dt−Δd + db) (2)
It becomes.

Since the displacement Δd due to this bending is detected by the output Δdr of the left and right laser beam position displacement detector 5R and the output Δdl of the laser beam position displacement detector 5L, the position calculator 15 detects this displacement. Can be obtained from the outputs of the left and right laser beam position detectors 5R and 5L based on the following equation.
Δd = (Δdr + Δdl) / 2 (3)

Therefore, in this case, the thickness correction unit 15 can obtain the correct thickness t with the displacement corrected based on the following equation from the output of the thickness calculation unit 11 and the output of the position calculation unit 15.
t = t ′ + Δd
= Ds− (dt−Δd + db) −Δd
= Ds- (dt + db) (4)

  In the present embodiment, it is assumed that the distance displacement at the optical distance detector 1B below the object to be measured 30 is small, and the displacement only at the top is detected and corrected. However, when the displacement at the bottom cannot be ignored. It is also possible to detect the displacement as a configuration similar to the upper displacement detection and correct the displacement on both sides.

  Next, referring to FIG. 5, the thickness measurement position is moved to the position xr in the x-axis direction, and the reference position Po of the optical distance detector 1T is the thermal strain of the upper guide rail 2T, and the point Pv Further, it is assumed that Δd (= Δdl + Δdxl) in the lower direction with respect to the reference position and the optical axis thereof is tilted to the right by Δθ with respect to the vertical direction.

  In this case, the output of the upper optical distance detector 1T is td 'shown in FIG.

  In this case, the left and right laser beam position detectors 5R and 5L detect Δdr and Δdl, respectively, and the output of the thickness measurement position control unit 13 and the preset movement stroke Ws are known (set values). Therefore, the values of Ws and measurement position xr are sent to the thickness position calculation unit 15 and the thickness position calculation unit 15 obtains the displacement.

The distance displacement from the reference position in the vertical direction is
xl = Ws-xr (5)
So
Δdxl = (Δdr−Δdl) × xl / (xl + xr) (6)
Further, the vertical displacement Δd (the displacement in the direction in which the thickness increases because the distance decreases) is obtained by the following equation.
Δd = Δdl + Δdxl (7)

Further, the inclination angle θ of the optical axis is obtained by the following formula.
cos θ = xl / (xl ² + Δdxl ² ) ^1/2 (8)

Therefore, the error Δθ (in this case, the displacement in the direction in which the thickness decreases because the distance increases) included in the output td ′ of the upper optical distance detector 1T is:
Δdθ = td ′ (1-cosθ) (9)

Therefore, the correction amount of the error with respect to the output t ′ of the thickness calculation unit 1 in this case is a value obtained by adding the error due to the vertical displacement Δd and the error Δθ due to the tilt displacement.
t = t ′ + (− Δd + Δdθ) (10)

  Here, the displacement from the reference position is assumed to be a displacement on the xz plane, but a three-dimensional displacement also occurs depending on the installation environment of the apparatus and the reference position setting structure of the optical distance detector. Therefore, it is necessary to select an optimal displacement detection as appropriate.

  According to the present embodiment, the displacement from the reference position of the pair of optical distance detectors is optically measured from the point light source (coordinates) provided on the optical base of the optical distance detector. Therefore, even if there is a thermal strain of the guide rail that supports the optical distance detector or a change with time, it can be easily corrected instantly without being affected by the reproducibility of the strain and the response time.

  As described above, in a thickness measurement device using an optical distance detector, the displacement of the distance from the reference position of the optical distance detector due to a change in the external temperature is detected, and simple heat insulation measures can be taken. It is possible to provide a thickness measuring device using an optical distance detector that can easily correct a thickness measurement error.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

1T, 1B Distance detector 2T, 2B Guide rail unit 3T, 3B Guide rail drive unit 4 Laser beam projection unit 4a Laser beam collimator 4b Beam splitter 5R, 5L Position displacement detector 11 Thickness calculation unit 13 Thickness measurement position control Unit 15 Position calculation unit 16 Thickness correction calculation unit 20 Gate-type frames 21 and 22 Thermal insulation cover 30 Object to be measured 50 Detection unit 60 Control unit 100 Thickness measurement device using an optical distance detector

Claims (4)

A pair of optical distance detectors for determining the distance to the object to be measured are provided opposite to the vertical direction of the object to be measured that moves in the horizontal direction, and the surface and the back surface of the object to be measured are set in advance. A thickness measuring device using an optical distance detector for obtaining a distance between each reference position in the vertical direction of the optical distance detector to obtain a thickness of the object to be measured,
A thickness measurement apparatus using the optical distance detector includes a detection unit and a control unit,
The detection unit spans the object to be measured, and a portal frame that supports the optical distance detector in a vertical direction at a thickness measurement position in the width direction of the object to be measured;
Both ends are fixed to the support of the portal frame, the optical distance detector provided on the surface side is moved to the thickness measurement position in the width direction of the object to be measured, and both ends are A lower guide rail that moves to the thickness measurement position, the optical distance detector that is fixed to the support of the portal frame and provided on the back surface side,
The optical distance detector on the surface side that is fixed to the upper guide rail, irradiates the surface of the object to be measured with a laser beam to obtain the distance from the position of the reflected light, and the laser is fixed to the lower guide rail. The optical distance detector on the back side for irradiating the back side of the object to be measured to obtain the distance from the position of the reflected light;
A laser beam projector that is fixed integrally with the optical base of the optical distance detector on the front side, and a laser beam that is fixed to the left and right columns of the portal frame and irradiated in the horizontal axis direction from the laser beam projector A pair of laser beam position detectors that receive light on a plane orthogonal to the laser beam and detect a light receiving position of the laser beam,
The control unit obtains a distance from the preset reference position from the optical distance detector on the front surface side and the output of the optical distance detector on the back surface side, and a thickness created in advance. A thickness calculator that calculates the thickness with reference to the calibration table;
From the outputs of the pair of laser beam position detectors, a distance displacement between the optical distance detector on the surface side and the reference position, and a distance displacement between the reference position due to an angular displacement with respect to the vertical direction. A position calculation unit that is obtained by referring to a pre-calibrated position calibration table;
A thickness measurement position controller that drives the upper and lower guide rails to move the optical distance detector on the front side and the optical distance detector on the back side to the thickness measurement position;
A thickness correction calculation unit that corrects a thickness output obtained by the thickness calculation unit with reference to a distance displacement with respect to a reference position of the optical distance detector obtained by the position calculation unit;
A thickness measuring apparatus using an optical distance detector.   The laser beam projector includes a laser beam collimator and a laser beam splitter, and the laser beam collimator generates one or two laser beams from a vertical direction. The thickness measuring apparatus using the optical distance detector according to claim 1, wherein the laser beam is irradiated in different directions along the horizontal axis. The thickness measuring apparatus using an optical distance detector according to claim 1, wherein the laser beam position detector is a line scan type CCD camera or an area scan type CCD camera.
  In the case where the object to be measured is a red-heated steel plate, the portal frame is configured so as to cover the periphery of the object to be measured, excluding the optical space between the detection unit and the object to be measured, The thickness measuring device using the optical distance detector according to claim 1, wherein the periphery of the detection section including the periphery of the optical distance detector is covered with a heat insulating cover that insulates the outside air.

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