JP2012229955A - Thickness measurement apparatus and thickness measurement method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thickness measurement device and a thickness measurement method which can correct a measurement error in a short time even if a set position of a distance detector is displaced.SOLUTION: The thickness measurement device comprises: a calibration plate 3 including a first thickness section and a second thickness section, which have reference thickness; a movement mechanism section 2 for moving a detection section 1; and a position setting section 4 for commanding movement to a "calibration position" with a constant length fixed in advance and a "measurement position" fixed in advance. The position setting section 4 delivers the "calibration" command to the movement mechanism section 2 to move the detection section 1 from the "measurement position" to the "calibration position", and delivers calibration position signals set in advance of the first thickness section and the second thickness section to a thickness arithmetic section 5. The thickness arithmetic section 5 determines each of thickness in the first thickness section and the second thickness section, determines a difference between the reference thicknesses, corrects the thickness determined at the "measurement position", fixes a thickness calibration plate, moves the detection section 1 and corrects the measurement error due to displacement of set positions of first and second distance detectors, which are set in advance.

Description

  The present invention relates to a thickness measuring apparatus and a thickness measuring method for measuring the thickness of a steel plate being conveyed using a distance detector using a laser beam.

  2. Description of the Related Art Devices that use a distance detector using a laser beam have become widespread as thickness measuring devices for shapes of various materials such as steel plates and products. This apparatus continuously measures the thickness of an object to be measured in the conveying direction.

  Compared to conventional thickness gauges using radiation, this thickness measurement device does not require special safety management, and the beam to be measured can be made smaller, so that changes in thickness can be measured with high resolution. It is. For this reason, it is used in a field where it is desired to accurately measure a sudden shape change near the end of the object to be measured.

  A configuration example of a thickness measuring apparatus 200 using this distance detector is shown in FIG. In FIG. 6, the detecting unit 1 of the thickness measuring apparatus 200 uses laser oscillators respectively placed on the upper part 1 a and the lower part 1 b of the arm parts of the C-shaped frame that sandwich the DUT 10. In the distance detector 11 and the distance detector 12 based on the principle of triangulation, the distance L1 and the distance L2 between each distance detector and the object to be measured 10 are respectively obtained, and the set distance L between the distance detectors is obtained. The thickness is obtained by calculation by setting it in advance and setting the thickness t of the DUT 10 to be t = L− (L1 + L2) from the set distance L and the obtained distances L1 and L2.

  Such a thickness measuring apparatus 200 periodically calibrates the thickness measurement value using a calibration piece called a calibration plate, which is a standard for thickness.

  However, in the detection unit 1 having a structure like a C-shaped frame, some external force is applied to the long arms (1a, 1b) that are the support mechanism of the distance detector, or ambient temperature or vibration of the installation location is applied. There is a problem that the set distance L between the distance detectors in the vertical direction with respect to the DUT 10 and the angles of the optical axes of the distance detector 11 and the distance detector 12 drift due to the environmental change.

  In order to eliminate this drift, a calibration apparatus is disclosed in which calibration pieces are set at high speed in the space of the C-shaped frame at regular intervals (see, for example, Patent Document 1).

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

  In the detection unit 1 of the thickness measuring apparatus 200 having a C-shaped frame as disclosed in Patent Document 1, as shown in FIG. 7, a C-shaped which is a support mechanism for the distance detector 11 and the distance detector 12. A change in the set distance L between the distance detectors (ΔL) due to a change in the environment of the long arm portion (1a, 1b) of the frame, or a distance detector set in the vertical direction with respect to the surface of the object to be measured 10 An error occurs due to an angle change (Δθ) of the measurement axis Lm.

  Specifically, the change (ΔL) in the set distance L is an error as shown in FIG. 8B. Further, the error due to the angle change (Δθ) of the optical axis Lm is an error proportional to the thickness t of the DUT 10 as shown in FIG.

  However, since the conventional calibration method using the calibration piece does not have a function of correcting the inclination of the optical axis Lm, an error due to an angle change (Δθ) of the optical axis Lm correlated with the thickness t of the object to be measured 10. There is a problem that cannot be corrected.

  Further, in the calibration of the thickness measuring apparatus 200 described above, it is necessary to temporarily retract the detection unit 1 at the measurement position (online position) to a position where the calibration operation can be performed (offline position) and then perform calibration. Therefore, there is a problem that the calibration time becomes long.

  The present invention has been made to solve the above-mentioned problems. In a thickness measuring apparatus using a distance detector, even if the set position of the distance detector is displaced, an error in the thickness measurement value can be obtained in a short time. An object of the present invention is to provide a thickness measuring apparatus and a thickness measuring method capable of correction.

  In order to achieve the above object, the thickness measuring apparatus of the embodiment is disposed on the upper and lower opposing arm portions of a C-shaped frame that sandwiches the object to be measured from the direction perpendicular to the conveying direction. A first distance detector for irradiating a surface of the object with a laser beam from a direction perpendicular to the object to be measured, and upper and lower arms of the C-shaped frame sandwiching the object to be measured; A second distance detector disposed at a lower portion of the first distance detector to obtain a distance from the measured object by irradiating a laser beam from a direction perpendicular to the back surface of the measured object; A thickness calculation unit that obtains a thickness from the output of the distance detector and the output of the second distance detector, wherein the detection unit includes a conveyance direction of the object to be measured; The first distance detection in one retraction position direction of the orthogonal direction A calibration plate comprising a first thickness portion and a second thickness portion having different preset reference thicknesses fixedly set within a measurement range of the measuring device and the second distance detector; A movement mechanism that moves the detection unit in a position direction and a measurement position direction opposite to the retraction position direction, and the movement mechanism unit includes the first thickness portion and the second thickness portion of the thickness calibration plate. A position detection sensor that detects a “calibration position” and a “measurement position” of the thickness portion, and a predetermined length “ A position setting unit that commands movement to a `` calibration position '' and a predetermined `` measurement position '', the position setting unit sends a `` calibration '' command to the movement mechanism unit, and the movement mechanism unit includes: The “measurement position” at a speed set in advance by the detection unit with the “calibration” command. To the “calibration position”, and a calibration position signal of the first thickness portion and the second thickness portion set in advance by a signal from the position detection sensor The thickness calculation unit obtains the thicknesses of the first thickness part and the second thickness part, obtains a difference from each of the reference thicknesses, and obtains it at the “measurement position”. The thickness calibration plate is fixed, the thickness calibration plate is fixed, and the detection unit is moved so as to correct a measurement error caused by a displacement of a preset position of the first and second distance detectors. It is characterized by that.

  In order to achieve the above object, the thickness measuring method of the thickness measuring apparatus according to the embodiment is arranged on the upper and lower arms of the C-shaped frame sandwiching the object to be measured from the direction orthogonal to the conveying direction. A first distance detector for irradiating a laser beam from a direction perpendicular to the surface of the object to be measured to obtain a distance from the object to be measured; and upper and lower sides of the C-shaped frame sandwiching the object to be measured. A second distance detector disposed below the arm portions facing each other and irradiating a laser beam perpendicularly to the back surface of the object to be measured to obtain a distance to the object to be measured. And a thickness calculation unit for obtaining a thickness from the output of the first distance detector and the output of the second distance detector, wherein the detection unit is configured to measure the measured object. In one retraction position direction in a direction orthogonal to the conveyance direction of the object, Calibration comprising a first thickness portion and a second thickness portion having different preset reference thicknesses fixedly set within the measurement range of the first distance detector and the second distance detector A plate, a retraction position direction, a movement mechanism portion that moves the detection portion in a measurement position direction opposite to the retraction position direction, and the movement mechanism portion includes the first thickness of the thickness calibration plate. And a position detection sensor for detecting the “calibration position” and the “measurement position” of the second thickness part, and the detection unit is determined in advance for the moving mechanism unit from the signal of the position detection sensor. A position setting unit that commands movement to a predetermined length of “calibration position” and a predetermined “measurement position”, and the position setting unit sends a “calibration” command to the movement mechanism unit, The moving mechanism unit moves the detection unit forward at a preset speed with the “calibration” command. The position is moved from the “measurement position” to the “calibration position”, and the calibration position signal of the first thickness part and the second thickness part set in advance by the signal from the position detection sensor. The thickness calculator calculates the thickness x at the “measurement position”, the average value m1 of the thicknesses of the first thickness part calculated at the “calibration position”, An average value m2 of the thickness of the second thickness portion is obtained, and when the reference thickness g1 of the first thickness portion and the reference thickness g2 of the second thickness portion are set in advance, The corrected thickness y is calculated as y = ((g2−g1) / (m2−m1)) · (x−m1) + g1 where m2> x> m1, the thickness calibration plate is fixed, The detector is moved to correct the measurement error due to the displacement of the preset position of the first and second distance detectors. The features.

1 is a configuration diagram of a thickness measuring apparatus according to Embodiment 1. FIG. FIG. 3 is a diagram for explaining an operation principle of the thickness measuring apparatus according to the first embodiment. 3 is a time chart for explaining the operation of the thickness measuring apparatus according to the first embodiment. The block diagram of the thickness measuring apparatus of Example 2. FIG. 9 is a time chart for explaining the operation of the thickness measuring apparatus according to the second embodiment. The block diagram of the conventional thickness measuring apparatus. The figure explaining the measurement error of the conventional thickness measuring apparatus.

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

  A thickness measuring apparatus 100 according to the first embodiment will be described with reference to FIGS. First, the measurement principle of the present invention will be described with reference to FIG. As shown in FIG. 7, in the thickness measurement apparatus 100 in which the configuration of the detection unit 1 measures the thickness using an optical distance detector on the arm portion of the C-shaped frame, the surface of the DUT 10 is measured. The distance is measured by irradiating the laser beam from the vertical direction.

  In such a thickness measuring apparatus 100, as described with reference to FIG. 7, the set distance L between the distance detectors is displaced (ΔL), or the optical axis of the laser beam of the distance detector is displaced (Δθ). As a result, a measurement error occurs.

  In order to correct such errors in a short time, the measurement principle of the present invention is that calibration plates having different thicknesses are set between the distance detectors, and the detector 1 being measured is orthogonal to the conveyance direction of the object 10 to be measured. In addition to moving in the retracting direction, the average value of a certain length of the thickness of the calibration plate placed on the retracting path is measured and corrected.

That is, calibration plates having two different reference thicknesses (g1, g2) having different predetermined lengths are provided at fixed positions, and the thickness is measured while the detector 1 is moved. The measured values are m1 and m2. Then, the thickness measurement value x measured in this state is obtained by the following equation (1).
y = (g2-g1) / (m2-m1). (x-m1) + g1 (1)
However, g2>x> g1.

  According to such a calibration method, when it is detected that the detector 1 is deformed for some reason or deformed by an external force, the detector 1 is moved in the retracting direction.

  In this case, the error correction of the measured thickness is corrected only by moving the detector 1 in the retracting direction using the detector moving mechanism without moving the thickness calibration plate serving as the thickness reference. be able to.

  In general, the thickness measuring apparatus 100 includes a thickness calibration table created in advance as a reference thickness as an initial value, and continuously measures the thickness of the DUT 10, but as described above. When it is detected that there is a change in the setting position for some reason, the error of the measured value can be immediately corrected in a short time.

  Next, the configuration of the first embodiment based on such a measurement principle will be described with reference to FIG.

  FIG. 1 shows a laser beam from a direction perpendicular to the surface of the object to be measured 10, which is disposed on the upper and lower arms 1 a of the C-shaped frame sandwiching the object to be measured 10 from a direction perpendicular to the conveying direction. A first distance detector 11 for irradiating a beam to obtain the distance to the object to be measured, and a lower part 1b of the upper and lower arms of the C-shaped frame sandwiching the object 10 to be measured, A detection unit 1 including a second distance detector 12 that obtains a distance from the object to be measured by irradiating a laser beam perpendicularly to the back surface of the object; and an output of the first distance detector 11; And a thickness calculator 5 for determining the thickness from the output of the second distance detector 12.

  Further, the detection unit 1 is fixedly set within the measurement range of the first distance detector 11 and the second distance detector 12 in one retraction position direction in a direction orthogonal to the conveyance direction of the DUT 10. A calibration plate 3 having a first thickness portion and a second thickness portion having different reference thicknesses set in advance, a detection portion in a retracted position direction and a measurement position direction opposite to the retracted position direction. A moving mechanism section 2 for moving 1 and a position reference for detecting a “calibration position” and a “measurement position” of the first thickness section and the second thickness section of the thickness calibration plate. Position detection sensors 41, 42, and 43 including a plate 40, and a predetermined length “calibration position” determined in advance with respect to the moving mechanism unit 2 based on a signal from the position detection sensor, and a predetermined position. The position setting unit 4 that commands movement is provided in the “measurement position”.

  Next, the detail of each part is demonstrated. The moving mechanism unit 2 places the detection unit 1 on the rail 21 when retracting from the measurement position to the calibration position, a plurality of wheels 23 provided below the detection unit 1, and the wheels 23 in the “measurement position” direction and “ And a drive unit 22 including a drive motor (not shown) that is rotated before and after the “retraction position direction”.

  The position setting unit 4 is provided on the detection unit 1 and a position reference plate 40 provided on the rail 21 for detecting the position of the detection unit 1. The position reference plate 40 detects the position of the detection unit 1 itself. The position detection sensor 41 and the position detection sensors 42 and 43 for detecting the “measurement position” and the “calibration position” are provided.

  As shown in the time chart of FIG. 3, the position detection unit 4 sends a measurement command signal s1 and a calibration command signal s2 to the drive unit 22, and the drive unit 22 sets the detection unit 1 in advance. The movement speed signal s3 is moved, the respective detection signals are received from the position detection sensors 41, 42, 43, and the "measurement position" signal s4 and the "calibration position" signals s5, s6 are generated to generate the thickness measurement unit Send to 5.

  Each of the thickness calibration plates 3 has a length Lw in the moving direction, and sets different reference thicknesses as average thicknesses g1 and g2 in the length Lw. It is made of a metal plate or the like that has a roughness and reflectivity approximate to the surface properties of the material and hardly changes over time.

  In addition, the thickness calculation unit 5 includes a calibration table with a thickness (not shown) generated by a distance signal from the distance detector 11 and the distance detector 12 and a calibration reference piece (not shown) set in advance. 4 receives the “measurement position” signal s4 sent from the sensor 4, measures the thickness of the device under test 10, and primarily stores it in a storage unit (not shown).

  When the “calibration position” signals s5 and s6 are received, the stored thickness measurement value x is subjected to the calculation of the above-described equation (1) to correct the thickness measurement value x.

  Next, the operation of the thickness measuring apparatus 100 calibrated in this way will be described with reference to FIG.

  First, the position setting unit 4 designates and sends a calibration command signal s1 and a movement speed signal s3 to the drive unit 22. Then, the drive part 22 drives the motor which is not shown in figure, rotates the wheel 23 in the direction of a measurement position, and moves the detector 1 to a measurement position.

  When the position setting unit 4 detects that the position detection sensor 41 has reached the “measurement position”, the position setting unit 4 instructs the drive unit 22 to stop driving the motor, and the position setting unit 4 outputs the “measurement position” signal s4. The thickness calculator 5 feeds, and the thickness calculator 5 starts measurement.

  The stop position of the detection unit 1 can also be controlled by the drive unit 22 itself.

  Next, during the thickness measurement of the object to be measured 10 or when there is a request for calibration to the detection unit 1 of the thickness measurement device 100, the operator of the thickness measurement device 100 moves the position setting unit 4. The calibration command signal s2 is sent to the drive unit 22 by operating.

  Then, the drive unit 22 moves the detection unit 1 in the retracting direction. When the position detection sensors 42 and 43 that are moving in the retracting direction are operated, the position setting unit 4 sends “calibration position” signals s5 and s6 to the thickness calculation unit 5 and instructs the thickness calculation unit 5 to perform a calibration calculation operation. .

Here, the signal width t _{DW of} the calibration position signals s 5 and s 6 and the signal width t _L between the calibration position signals s 5 and s 6 are the lengths Lw in the moving direction of the reference thicknesses g 1 and g 2 of the thickness calibration plate 3, Further, the length Lw of the thickness portion and the surface property of the thickness calibration plate 3 which are set in advance and correspond to the distance Ls between the reference thickness and the reference thickness are the thicknesses at the moving speed of the detection unit 1. The variation of the average value is set so as to be within a predetermined value range.

The thickness calculation unit 5 receives the “calibration position” signals s5 and s6 transmitted from the position setting unit 4, obtains average values m1 and m2 of the thickness between the signal widths t _DW , and is described above ( 1) The obtained thickness measurement value x is corrected by the equation.

  According to the thickness measuring apparatus of such an embodiment, when an abnormality in the setting position of the detector is detected for some reason, the measured thickness can be corrected in a short time by moving the detection unit to the retracted position. It becomes possible.

  Embodiment 2 will be described with reference to FIGS. 4 and 5. About each part of Example 2, the same part as Example 1 attaches | subjects the same code | symbol, and abbreviate | omits the description. The difference between the second embodiment and the first embodiment is that, in the first embodiment, the thickness calibration plate 3 sets a different reference thickness. In the second embodiment, this thickness calibration is further performed. The storage case 31 for storing the plate 3 is provided.

  More specifically, the position setting unit 4 sends signals for opening and closing the storage case from the position detection sensors 42 and 43 to the drive unit of the storage case 31 (not shown). The drive unit receives the position detection sensor 42 and receives the position detection sensor 42 in advance. The storage case 31 is opened, and calibration position signals s7 and s8 of the thickness calibration plate 3 are generated in this state, and further, a storage case closing signal is generated from the position detection sensor 43.

  That is, the position detection sensors 42 and 43 use the storage case only during the period when the thickness calibration plate 3 is used, and store it in the storage case during other periods to prevent the thickness calibration plate 3 from changing over time. As a result, the quality of the thickness calibration plate of the distance detector, which is an optical measuring device, can be used stably for a long period of time.

  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 Detection part 1a Upper part of arm part 1b Lower part of arm part 11 First distance detector 12 Second distance detector 2 Moving mechanism part 21 Rail 22 Drive part 23 Wheel mechanism part 3 Thickness calibration plate 31 Storage case 4 Position Setting unit 40 Position reference plate 41 Position detection sensor 42 Position detection sensor 43 Position detection sensor 5 Thickness calculation unit 10 DUT 100, 200 Thickness measurement device

Claims (4)

The object to be measured is placed on the upper and lower arms of the C-shaped frame that sandwiches the object to be measured from the direction perpendicular to the conveying direction, and the surface of the object to be measured is irradiated with a laser beam from the vertical direction to irradiate the object. A first distance detector for determining the distance to the object to be measured, and a lower part of the upper and lower arms of the C-shaped frame sandwiching the object to be measured, perpendicular to the back surface of the object to be measured A second distance detector for obtaining a distance from the object to be measured by irradiating a laser beam from
A thickness calculator that calculates a thickness from the output of the first distance detector and the output of the second distance detector,
The detection unit is fixedly set in advance within a measurement range of the first distance detector and the second distance detector in one retraction position direction in a direction orthogonal to the conveyance direction of the object to be measured. A calibration plate comprising a first thickness portion and a second thickness portion having different set reference thicknesses;
A moving mechanism unit that moves the detection unit in the retraction position direction and a measurement position direction opposite to the retraction position direction;
The moving mechanism section includes a position detection sensor for detecting “calibration position” and “measurement position” of the first thickness section and the second thickness section of the thickness calibration plate, and the position detection sensor. From the signal, a position setting unit for commanding the movement to the movement mechanism unit to a predetermined “calibration position” of a predetermined length and a predetermined “measurement position”;
With
The position setting unit sends a “calibration” command to the moving mechanism unit, and the moving mechanism unit moves the detection unit from the “measurement position” to the “calibration position” at a speed set in advance by the “calibration” command. To
Further, a signal from the position detection sensor sends a preset calibration position signal of the first thickness part and the second thickness part to the thickness calculation part,
The thickness calculator obtains the thicknesses of the first thickness part and the second thickness part, obtains a difference from each of the reference thicknesses, and obtains the thickness obtained at the “measurement position”. To correct
The thickness calibration plate is fixed, and the detection unit is moved to correct a measurement error due to a preset displacement of the set positions of the first and second distance detectors. Thickness measuring device. The thickness calculation unit sets the thickness obtained at the “measurement position” to x, an average value of the thicknesses of the first thickness part obtained at the “calibration position”, and the second thickness part. Are the average thicknesses m1, m2 (m2> m1), the first reference thickness g1 of the first thickness portion, and the reference thickness g2 of the second thickness portion, respectively. ,
The corrected thickness y is m2>x> m1,
y = ((g2-g1) / (m2-m1)) * (x-m1) + g1
The thickness measuring device according to claim 1, which is obtained as follows. Further, the thickness calibration plate includes a storage case,
After the “calibration” command, the position setting unit “opens” the storage case in front of the thickness calibration plate and “closes” after passing the thickness calibration plate by a signal from the position detection sensor. The thickness measuring device according to claim 1, wherein the opening / closing of the storage case is commanded. The object to be measured is placed on the upper and lower arms of the C-shaped frame that sandwiches the object to be measured from the direction perpendicular to the conveying direction, and the surface of the object to be measured is irradiated with a laser beam from the vertical direction to irradiate the object. A first distance detector for determining the distance to the object to be measured, and a lower part of the upper and lower arms of the C-shaped frame sandwiching the object to be measured, perpendicular to the back surface of the object to be measured A second distance detector for obtaining a distance from the object to be measured by irradiating a laser beam from
A thickness calculator that calculates a thickness from the output of the first distance detector and the output of the second distance detector,
The detection unit is fixedly set in advance within a measurement range of the first distance detector and the second distance detector in one retraction position direction in a direction orthogonal to the conveyance direction of the object to be measured. A calibration plate comprising a first thickness portion and a second thickness portion having different set reference thicknesses;
A moving mechanism unit that moves the detection unit in the retraction position direction and a measurement position direction opposite to the retraction position direction;
The moving mechanism section includes a position detection sensor for detecting “calibration position” and “measurement position” of the first thickness section and the second thickness section of the thickness calibration plate, and the position detection sensor. From the signal, a position setting unit for commanding the movement to the movement mechanism unit to a predetermined “calibration position” of a predetermined length and a predetermined “measurement position”;
With
The position setting unit sends a “calibration” command to the moving mechanism unit, and the moving mechanism unit moves the detection unit from the “measurement position” to the “calibration position” at a speed set in advance by the “calibration” command. To
Further, a signal from the position detection sensor sends a preset calibration position signal of the first thickness part and the second thickness part to the thickness calculation part,
The thickness calculator calculates the thickness x at the “measurement position”,
An average value m1 of the thickness of the first thickness portion obtained at the “calibration position”, and an average value m2 of the thickness of the second thickness portion;
Further, assuming that the reference thickness g1 of the first thickness portion and the reference thickness g2 of the second thickness portion that are set in advance are set, the corrected thickness y is m2>x> m1,
y = ((g2-g1) / (m2-m1)). (x-m1) + g1
As sought
The thickness calibration plate is fixed, and the detection unit is moved to correct a measurement error due to a preset displacement of the set positions of the first and second distance detectors. Thickness measuring method of thickness measuring device.

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