JPH04116409A - Automatic plate thickness measuring device - Google Patents

Abstract

PURPOSE:To compensate for the strain in a frame and the change in characteristics of optical displacement gages in calibration and to make it possible to measure the thickness of a plate accurately by correcting the outputs of the optical displacement gages and a reference distance based on a linearity correcting table and a calibration table. CONSTITUTION:The outputs of optical displacement gages are made to correspond to the expected upper and lower positions of the optical displacement gages 18 in linearity calibration with a linearity correcting means based on a linearity correcting table. Such a table is prepared. A reference distance is obtained based on the outputs of the optical displacement gages 18 when a frame is calibrated and the plate thickness of a calibrating plate 28 with a frame correcting means. A calibrating table by which the reference distance is made to correspond to the right and left positions of the optical displacement gages 18 is prepared. Then, the distance between each optical displacement gage 18 and a body under measurement 10 is corrected in reference to the linearity correcting table with a plate-thickness operating means. The reference distance is corrected in reference to the calibrating table based on the right and left positions of the optical displacement gages 18. The plate thicknesses of the body under measurement 10 are operated and averaged at several points on the locus based on the upper and lower moving amounts of the optical displacement gages 18, the corrected distances and the reference distance. Thus, the plate thickness can be measured accurately.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an automatic plate thickness measuring device that automatically measures the plate thickness of an object to be measured conveyed by a conveyance line in a non-contact manner by reflecting a light beam.

[Prior Art] Conventionally, an automatic plate thickness measuring device has been known that automatically measures the plate thickness of a measured object transported by a transport line using an optical displacement meter (for example, Japanese Patent Publication No. 5610561).

The device used in the past is a one-point old measurement device using a so-called C-shaped frame, and the object to be measured is a fixed width object, that is, a fixed width object. .

In this device, optical displacement gauges are placed above and below the conveyance line. This optical displacement meter irradiates a light beam, which is a laser beam, to the target 7Il11 and measures the thickness of the target d1.

Conventionally, such a device has been used to automatically measure the thickness of an object to be measured such as a steel plate.

By the way, in general, calibration is required to ensure the accuracy of automatic plate thickness measuring devices.

Calibration is performed each time the device is used, and is an essential step in device operation. More specifically, errors due to aging of the optical displacement meter are corrected (electrical correction), mechanical distortion is corrected (mechanical correction), reliability is maintained, and accurate plate thickness 14111 is corrected. It is expected that the

[Problems to be Solved by the Invention] However, in the past, there was a problem in that errors occurred in plate thickness measurements due to distortion of the pedestal, changes in characteristics of the optical displacement meter, and the like.

In other words, the optical displacement meter is attached to a pedestal on the second conveyor line, and as long as this pedestal maintains a predetermined position and shape, no error will occur due to the pedestal. However, in reality, distortion occurs in the frame due to environmental factors such as temperature, humidity, etc., and changes over time. This distortion causes
The amount of movement of the optical displacement meter changes non-linearly, causing an error in plate thickness measurement.

Furthermore, the detection characteristics of the optical displacement meter also change due to similar factors. This change also causes errors in plate thickness measurements.

Furthermore, in the past, there has been a problem in that sometimes only the surface properties of the same object can be measured. That is, if the surface texture of each object to be measured differs, it becomes difficult to perform accurate measurements using a device calibrated according to one type of surface texture. Furthermore, if the surface properties of a single object to be measured are not constant, the measurement becomes impossible.

The present invention was made with the aim of solving these problems, and it is an object of the present invention to compensate for mount distortion, changes in characteristics of the optical displacement meter, etc. during calibration, thereby making it possible to perform more accurate plate thickness measurements. With the goal. Another object of the present invention is to make it possible to simultaneously and accurately determine objects to be measured having different surface textures, or to measure objects to be measured that have non-uniform surface textures.

[Means for Solving the Problems] In order to achieve such an object, the present invention provides a pair of mounts arranged on the upper and lower mounts of the conveyance line for conveying the object to be measured and separated by a predetermined reference distance. A plurality of pairs of optical displacement meters are arranged and have an L-shaped bend at the tip, and a plurality of pairs of optical displacement meters that emit a light beam to the measured object and measure the distance to the measured object based on the reflected light.
When measuring the plate thickness of the object to be measured, a calibration plate with a predetermined thickness is placed at the tip or outside the measurement area of the optical displacement meter, and during calibration, the tip is calibrated so that it is located at a predetermined position that blocks the light beam emitted from the optical displacement meter. There is a rotating means for rotating the plate, and during measurement, the vertical position of the optical displacement meter is controlled so that the position is determined according to the plate thickness standard of the object to be measured, and the vertical position of the optical displacement meter is controlled according to the flow of the object to be measured. The left and right positions of the optical displacement meter are controlled to draw a predetermined trajectory on the measuring object, and during linearity calibration, the optical displacement meter is moved vertically at a predetermined pitch, and during mount calibration, the optical displacement meter is moved at a predetermined interval in the left and right direction. a linearity correction means for creating a linearity correction table that associates the output of optical displacement A-1 with the expected vertical position of the optical displacement meter during linearity calibration; A mount correction means that calculates a reference distance based on the output of the displacement meter and the thickness of the calibration plate, and creates a calibration table that associates this reference distance with the left and right positions of the optical displacement meter, and a linearity correction table. Correct the distance between the optical displacement meter and the JIIJ object, and correct the reference distance by referring to the calibration table based on the left and right positions of the optical displacement meter, and calculate the vertical movement amount of the optical displacement meter, the corrected distance, and the reference distance. The present invention is characterized by comprising a plate thickness calculation means for calculating and averaging the plate thickness of the object to be measured for several points along the trajectory based on the above-mentioned trajectory.

[Function] In the automatic plate thickness measuring device of the present invention, the distance between the optical displacement meter and the object to be measured, the amount of vertical movement of the optical displacement meter, and the reference distance between the opposing optical displacement meters, is used to determine the distance between the optical displacement meter and the object to be measured. The plate thickness is required.

Among these, the distance between the optical displacement meter and the object to be measured is corrected by the linearity correction table.

For example, if the characteristics of the optical displacement meter have changed from the initial characteristics, errors will occur in the plate thickness measurements unless this change is compensated for. Therefore, in the present invention, linearity calibration is performed. Linearity calibration is performed while moving the optical displacement meter at a predetermined pitch in the vertical direction, and in this calibration, the output of the optical displacement meter is associated with the expected vertical position of the optical displacement meter.

The output of the optical displacement meter at this time indicates the distance between the optical displacement meter and the calibration plate. That is, during calibration, the calibration plate is rotated to a position that blocks the light beam, and reflected light is obtained from this calibration plate. Further, the expected vertical position is, for example, a vertical position obtained by position control based on the initial characteristics of the optical displacement meter.

The table showing the correspondence between the output of the optical displacement meter and the vertical position will be referred to as a linearity correction table.

This linearity correction table is used to correct the output of the optical displacement meter during measurement, that is, the distance between the optical displacement meter and the object to be measured. This compensates for the error caused by the above-mentioned change in characteristics depending on the vertical position of the optical displacement meter during measurement.

Further, the distance between the optical displacement meter and the object to be measured is corrected using a calibration table.

For example, if the pedestal is distorted, measurement errors may occur due to this distortion. Therefore, in the present invention, pedestal calibration is performed. The gantry calibration is performed by moving the optical displacement meter in the left-right direction at predetermined intervals and based on the output of the optical displacement meter at that time.

More specifically, a calibration table is created that associates the reference distance determined from the output of the optical displacement meter with the left and right positions of the optical displacement meter. The reference distance in this case is determined based on the outputs of the upper and lower optical displacement meters and the known thickness of the calibration plate.

The calibration table obtained in this way is used to correct the reference distance during measurement. This reduces errors that occur depending on the left and right positions of the optical displacement meter during measurement, such as errors caused by frame distortion. Note that it is preferable to perform the gantry calibration using the results after the linearity calibration.

Furthermore, during measurement, a spatial average calculation is performed. During measurement, the left and right positions of the optical displacement meter are controlled so as to draw a predetermined locus on the object to be measured. In the present invention, the plate thicknesses at a predetermined number of points are determined along this trajectory and averaged. Therefore,
In the present invention, the number of points that serve as the basis for plate thickness calculation increases, so the accuracy of measurement improves.

[Examples] Hereinafter, preferred embodiments of the present invention will be described based on the drawings.

FIG. 1 shows the actual configuration of an automatic plate thickness measuring device according to an embodiment of the present invention. In particular, FIG. 1(a) shows the external appearance of the device as seen from above, and FIG. 1(b) shows the external appearance of the device as seen from the side.

This figure shows a conveyance line 12 that conveys the object to be measured 10 in the direction indicated by the arrow in the figure. The objects 10 to be measured in this figure are steel plates having different thicknesses, widths, etc., and three objects 101.10-2.10-3 are shown in the figure.

In this embodiment, the measuring object 10 to be measured has a thickness of 4 to 60 mm, a width of 800 to 4000 mm,
It has a standard length of 1,500 to 14,000 mm, and is placed at any position on the conveyance line 12 in any orientation.

Further, a pair of upper and lower concave pedestals 14 are provided so as to straddle the transport line 12 . Conveyance line 1 of concave pedestal 14
2, a line sensor 16 is provided on the upstream side, and an optical displacement meter 18 is provided on the downstream side.

A pair of line sensors 16 are provided on both the vertical and vertical gate-shaped mounts 4, and detect the positions of both left and right ends of the tip of the object to be measured 10. The detected left and right end positions are used for initial setting of the position of the optical displacement meter 18.

Further, three pairs of optical displacement meters 18 are movably provided on the concave pedestal 14. This optical displacement meter 18 is a device for measuring the plate thickness of the object to be measured. That is, the optical displacement meter 18 irradiates the object to be measured 0 with a light beam and captures the reflected light. Further, the distance to the object to be measured 10 is determined based on the captured reflected light, and the distance is used to calculate the plate thickness based on the principle described later.

FIG. 2 shows a more detailed front view of this embodiment.

In this figure, two linear motor rails 20, upper and lower, are shown. The linear motor rail 20 is a linear motor rail that drives each of the six optical displacement meters 18 in the left and right directions.

Further, the upper three optical displacement meters 18 are attached to the pulse stage 22. That is, these three optical displacement meters 18 are driven in the vertical direction by the pulse stage 22, and during measurement, the vertical position is set by controlling the pulse stage 22 according to the plate thickness standard of 7It++ + regular holidays 10.

Furthermore, of the three pairs of optical displacement meters 18, two pairs on both the left and right sides have
First and second edge sensors 24 and 26 are provided. The first edge sensor 24 is used to further finely adjust the position of the optical displacement meter 18, which is initially set according to the output of the line sensor 16. The second edge sensor 26 is used to follow and detect the side edge of the object to be measured 10.

FIG. 3 shows a device configuration related to the calibration of the optical displacement meter 18 in this embodiment. In particular, FIG. 3(a) shows the front of the pair of optical displacement meters 18, and FIG. 3(b) shows the side.

In this figure, a calibration plate 28 is shown which is rotatably arranged at a position shown by a broken line during normal plate thickness measurement and at a position shown by a solid line during calibration. The calibration plate 28 has an L-shaped bend, and the plate thickness at the tip is set to a predetermined thickness that has been certified. The calibration plate 28 is rotated by a rotary solenoid 30. Further, the calibration plate 28 is vibrated in the horizontal direction with an amplitude of, for example, ±3 mm by a motor (not shown).

FIG. 4 shows the circuit configuration of this embodiment.

In this figure, on the one hand, the thickness of the object to be measured 10 is determined based on the output of the optical displacement meter 18, and on the other hand, the line sensor] 6
Also shown is an arithmetic control section 34 that controls the linear motor 32 and pulse stage 22 based on the outputs of the first and second edge sensors 24 and 26. Furthermore, the calculation control section 34 also controls the rotary solenoid 30. In addition,
This figure shows a memory 36 that stores a reference distance determined during calibration and a linearity correction table related to the features of the present invention. In addition, optical displacement meter 18, line sensor] 6
, the first edge sensor 24, the second edge sensor 26, the linear motor 32, the pulse stage 22, and the rotary solenoid 30 are actually plural, or are omitted in this figure for simplicity.

Next, the operation of this embodiment will be explained.

First, the object to be measured]0 is placed on the transport line 12. The placed object 10 to be measured is transported by the transport line 12 and reaches below the line sensor] 6.

Then, the line sensor 16 detects the light-blocking position caused by the object to be measured]0. That is, line sensor 1
6 detects the portion where the light beam is blocked by the target al11 regular holiday 10, and supplies this to the arithmetic control unit 34 as the left and right end positions of the target 1'1l11 regular holiday]0.

The calculation control unit 34 drives and controls the linear motor 32 based on the output of the line sensor 16 to control the position of the optical displacement meter 18 . Specifically, one pair of optical displacement meters 18 on both the left and right sides
A pair of optical displacement meters 1 located in the center are moved to both left and right end positions of the object to be measured 10, which are detected as light shielding positions.
8 is maintained at the center position of the left and right optical displacement meters 18. This initializes the position of the optical displacement meter 18.

Thereafter, when the object to be measured]0 is further transported and reaches the first edge sensor 24, the position of the optical displacement meter 1-8 is finely adjusted by the first edge sensor 24.

That is, the calculation control section 34 controls the linear motor 32 according to the output of the first edge sensor 24.

Next, both left and right ends of the object to be measured 10 are captured by the second edge sensor 26 . At this time, the calculation control section 34 controls the linear motor 32 based on the output of the second edge sensor 26. That is, since the second edge sensor 26 is fixed to the optical displacement meter 18, this control allows the second edge sensor 26 to continue tracking and capturing both the left and right ends of the object to be measured 10.
The optical displacement meters 18 on both the left and right sides detect and scan a locus at a predetermined distance from both the left and right ends of the object 10 to be measured.

FIG. 5 shows the light beam locus of the optical displacement meter 18, and FIG. 6 shows the points (measurement positions) of this locus used for plate thickness calculation.

In this embodiment, the output of the optical displacement meter 18 related to the trajectory indicated by the three arrow lines in FIG. 5 is continuously collected. After this collection, the calculation control unit 34 determines the measurement position and calculates the plate thickness.

More specifically, the calculation control unit 34 controls the first edge sensor 2 after the tip of the object to be measured 10 reaches the line sensor 16.
The conveying speed of the target δIII constant body 10 is determined from the time taken to reach the δIII constant body 10. Line sensor 16 and first edge sensor 2
Since the distance 4 is determined by design, the time can be converted into position coordinates with respect to the object to be measured 10 using this transport speed. Based on this conversion result, the measurement position is determined.

The δIII fixed position is determined, for example, from a total of six lines: a line 15 mm from both the left and right ends of the object to be measured 10, a line 15 nm from both the front and rear ends, and a center line. That is, the intersection points of these lines are set at measurement positions P□ to P9.

Next, for the measurement positions Pe to P9 set in this way, the calculation control unit 34 performs plate thickness calculation based on the output of the optical displacement meter 18 that has not yet been collected.

In the case of this embodiment, the data used for the plate thickness calculation is the spatial average of points in the vicinity of each measurement position P□ to P.

FIG. 7 shows the calculation contents of the spatial average.

As shown in this figure, the measurement position P and 10 points each before and after the measurement position P are taken as primary valid data.

Each point is set at a pitch of 2 mm, and the spatial average is calculated using only those points that meet a certain condition out of a total of 21 points.

For example, out of 21 points, delete 2 points from the maximum value, 5 points from the minimum value, and also delete abnormal values, so that the remaining points become 1.
In the case of 0 points or more, the optical displacement meter 1 for the remaining points
The 8 outputs are averaged. Note that if the score does not reach 10 points, it is determined that measurement is not possible.

The plate thickness calculation in this embodiment is performed according to a predetermined principle using the distance between the optical displacement meter 18 and the object to be measured 10, which is thus obtained as a spatial average.

FIG. 8 shows the principle of plate thickness measurement in this embodiment.

In this embodiment, the thickness of the board 10 is determined based on the distance between the opposing optical displacement gauges 18 when measuring the board thickness and the above-mentioned spatial average.

First, the facing distance of the optical displacement meter 18 without the object to be measured 10, that is, the reference distance. is determined by design. Further, in the case of the measured object 10 having a thick plate, the amount by which the distance between the optical displacement meters 18 is increased, that is, the amount of movement of the optical displacement meters 18 is defined as L3.

Then, the distance L measured by the upper optical displacement meter 18
□ and the distance L measured by the lower optical displacement meter 18
2, the plate thickness can be determined using the following formula.

L==(Lo+L3)-(L1+L2) In this way, in this embodiment, multi-point measurement of the plate thickness is performed based on the measurement positions P1 to P9. At this time, since the spatial average is used, a certain degree of accuracy is ensured even when the surface properties of the target 711 and the regular holiday 10 are uneven. In other words, by spatial averaging, the non-uniformity of the output of the optical displacement meter 18 due to the surface texture is absorbed. Furthermore, even if the surface texture of the same object 10 to be measured is non-uniform, this will be absorbed in the same way, making measurement possible.

Furthermore, in this embodiment, the moving ML used to measure plate thickness has a value corrected by a linearity correction table created for each optical displacement meter 18 during calibration.

Next, the calibration operation related to the creation of this linearity correction table will be explained.

The optical displacement meter 18 is a device whose characteristics change due to environmental factors, change over time, etc., for example. In FIG. 9, the solid line shows the initial characteristic, and the broken line shows the changed characteristic.

Such a change in characteristics appears as an error during measurement. Therefore, in this embodiment, linearity calibration is performed as the calibration.

Further, if the pedestal 14 is distorted due to temperature, humidity, aging, etc., this distortion changes the distance between the upper and lower optical displacement meters 18, that is, the reference distance.

This change appears as an error in the measured value. For this reason,
In this embodiment, frame calibration is performed.

Linearity calibration is performed prior to gantry calibration.

That is, after the linearity calibration has been performed, the mount calibration is performed on the optical displacement meter]8.

First, during linearity calibration, the calibration plate 28 is rotated by the rotary solenoid 30. As a result of this rotation, the tip is placed at a position between the optical displacement meters 18 facing each other.

The calibration plate 28 is made of a white ceramic plate with a known thickness, and is vibrated in the horizontal direction by the rotary lenoid 30 after placement. This vibration has an amplitude of ±3mm
This vibration is applied to eliminate the influence of the surface properties of the calibration plate 28.

In this state, the optical displacement meter 18 is moved downward by a predetermined pitch. That is, the pulse stage 22 is controlled by the arithmetic control unit 34, and the upper optical displacement stage 18 is controlled by the pulse stage 22.
The 1-lower position changes at a predetermined pitch, for example, 1 mm. An output from the optical displacement meter 18 is obtained for each change. This output indicates the distance between the optical displacement meter 18 and the calibration plate 28. The 71111 determination is performed 16 times for each pitch, and after the optical displacement meter 18 is moved vertically a predetermined number of pitches, for example, the number of pitches corresponding to ±20 mm, these outputs are averaged.

The average of the optical displacement meter 18 outputs obtained in this way (hereinafter cl and t are referred to as the optical displacement meter 18 outputs) is the optical displacement meter 18 output.
This corresponds to the expected vertical position of 8. That is,
The output of the optical displacement meter 18 is associated with the expected vertical position and stored in the memory 36 as a linearity correction table.

FIG. 10 shows an example of a linearity correction table.

As shown in this figure, the linearity correction table associates the control amount (command value) L38□ of the pulse stage 22 by the calculation control unit 34 with the actual output L3A of the optical displacement meter 18. The command value L3S i is a value issued based on the initial characteristics of the optical displacement meter 18, and would be obtained if the characteristics of the optical displacement meter 18 had not changed.
That is, it is an ideal value. Therefore, the linearity correction table associates ideal values and actual values regarding the characteristics of the optical displacement meter 18.

Such a linearity correction table is created for each of the upper optical displacement meters 18 for the purpose of responding to changes in the characteristics of the optical displacement words 18.

In this way, after the linearity calibration is performed, the mount calibration is performed. In this pedestal calibration, the optical displacement meter 18 and the calibration plate 28 below 1 are horizontally moved together.

That is, as shown in FIG. 11, the movable ranges of the three optical displacement meters 18 are 1.00-1, ]00-2, and 100.
-3 (for example, about 40 mm), and covers the full width of the conveyance line [2]10. Optical displacement meter 1
8 and the calibration plate 28 are integrally moved at predetermined intervals within their respective movable ranges 100, and a calibration table is created for each optical displacement meter 18.

An example of a calibration table is shown in FIGS. 1-2.

As shown in this figure, the calibration table is a table that associates the left-right position X of the optical displacement meter with the actual reference distance LoAi at each left-right position XAi.

In pedestal calibration, as in the case of linearity calibration, use the calibration plate 2.
8 is rotated and horizontally vibrated.

The output of the optical displacement meter 18 in this state indicates the distance between the optical displacement meter 18 and the calibration plate 28.

Here, the thickness of the calibration plate 28 is β. , the distances from the upper and lower optical displacement meters 18 to the calibration plate 28 (that is, the respective outputs of the upper and lower optical displacement meters 18) are Ω and 1l12, respectively. In this case, as shown in FIG. 3, the following formula % formula % holds true for the reference distance Lo. Therefore, the actual reference distance Lo is determined by the calculation control unit 34 executing the calculation based on the above equation. Further, such calculations are repeated a predetermined number of times, for example, 16 times, and the average value is obtained, and this average value is used as the reference distance. If you treat it together, the standard distance will be further increased. accuracy will be improved.

This standard distance. is obtained as N pieces of data LoAi by moving the upper optical displacement meter 18 left and right at predetermined intervals. Note that this left and right movement is performed by the calculation control section 34.
This is performed by the linear motor 32 based on the control of.

When the reference distance "OAi" obtained in this way is correlated with the left and right positions of the optical displacement meter 18, a calibration table as shown in FIG. 11 is created.The calibration table is
It is created for each pair of optical displacement meters 18.

The linearity correction table and calibration table created as described above are stored in the memory 36.

During measurement, these linearity correction tables and calibration tables are referred to.

That is, when determining the thickness of the object to be measured 10, the calculation control unit 34 reads data in the linearity table based on the command value to the pulse stage 22.

The data obtained by this reading is, for example, L in FIG. 9. Therefore, by finding the difference between this data A1 and the command value, the error caused by the characteristic change included in the current output of the optical displacement meter 18 can be found. By subtracting this error from the output of the optical displacement meter 18, the influence of the error caused by the change in the characteristics of the optical displacement meter 18 is eliminated.

In addition, in order to correct the reference distance used when calculating the plate thickness by L○, the calculation control unit 34 reads data related to the calibration table from the memory 36 based on the left and right positions of the optical displacement meter 18. The read data is the reference distance related to the left and right positions @
L □. This standard distance. As described above, is a value that reflects the distortion of the pedestal, so if the plate thickness is calculated using this reference distance Lo, it is possible to prevent errors from occurring when the pedestal 14 is distorted.

In this way, according to this embodiment, electrical correction and mechanical correction can be performed at once using the calibration plate 28 using simple means. Furthermore, correction can be performed using the linearity correction table and the calibration table, and it becomes possible to calculate the plate thickness more accurately and ensure accuracy and reliability.

In addition, the distance between the optical displacement meter 18 and the object to be measured 10 is determined as a spatial average of several points near the measurement point, and as a result, it is possible to determine the distance between the optical displacement meter 18 and the object to be measured 10.
Even if there is some variation in the surface texture at 0, the influence of this surface texture can be corrected and the plate thickness can be measured more accurately.

Note that in the above description, the pulse stage 22 was provided only on the upper side, but it may also be provided on the lower side. in this case,
Linearity correction tables are created for the upper and lower optical displacement meters 18, allowing more precise measurements.

[Effects of the Invention] As explained above, according to the present invention, a linearity correction table and a calibration table are created, and the optical displacement meter output and reference distance are corrected using the linearity correction table and the calibration table. Enables more accurate plate thickness measurement. Furthermore, since the plate thickness is calculated based on a spatial average, errors caused by surface properties are reduced, making it possible to measure the plate thickness more accurately.

[Brief explanation of drawings]

FIG. 1 is a schematic external view showing the actual configuration of an automatic plate thickness measuring device according to an embodiment of the present invention, in which FIG. 1(a) is a top view, FIG. 1(b) is a side view, and FIG. The figure is a front view showing a more detailed actual configuration of this embodiment, and FIG. 3 is a schematic diagram showing the configuration of the calibration means of this embodiment. ) is a side view, Figure 4 is a block diagram showing the circuit configuration of this embodiment, Figure 5 is a diagram showing the locus of the light beam emitted from the optical displacement meter, Figure 6 is a diagram showing the plate thickness measurement position, Figure 7 is a diagram showing the concept of spatial averaging, Figure 8 is a diagram showing the principle of plate thickness measurement, Figure 9 is a diagram showing changes in characteristics of the optical displacement meter, and Figure 10 is an example of a linearity correction table. FIG. 11 is a diagram showing the movement range of the optical displacement meter, and FIG. 12 is a diagram showing an example of a calibration table. ]0... Object to be measured 12/Transportation line]8... Optical displacement meter 32... Calibration plate Rotary solenoid linear motor calculation control section

Claims (1)

[Claims] The system is arranged in pairs on the upper and lower mounts of the transport line that transports the object to be measured, and is spaced apart by a predetermined reference distance, and irradiates the object with a light beam and based on the reflected light. A plurality of pairs of optical displacement meters that measure the distance to the object to be measured, and a predetermined plate thickness whose tip has an L-shaped bend and whose tip is placed outside the measurement range of the optical displacement meter when measuring the thickness of the object to be measured. a calibration plate; a rotating means for rotating the calibration plate so that its tip is located at a predetermined position that blocks the light beam emitted from the optical displacement meter during calibration; The vertical position of the optical displacement meter is controlled so that it is at the determined position, and the horizontal position of the optical displacement meter is controlled so that it draws a prescribed trajectory on the measured object according to the flow of the measured object. A position control means that moves the displacement meter vertically at a predetermined pitch, and moves the optical displacement meter at a predetermined interval in the left and right direction during frame calibration, and a position control means that moves the optical displacement meter at a predetermined interval in the horizontal direction when calibrating the mount, and a position control means that moves the optical displacement meter at a predetermined interval during linearity calibration. A linearity correction means that creates a linearity correction table that corresponds to the vertical position of a gantry correction means that creates a calibration table that corresponds to the left and right positions of the optical displacement meter; plate thickness calculating means for correcting the reference distance, calculating and averaging the plate thickness of the object to be measured at several points along the trajectory based on the vertical movement amount of the optical displacement meter, the corrected distance, and the reference distance; An automatic plate thickness measuring device characterized by: