JPH04116411A - Automatic plate-thickness measuring apparatus - Google Patents

Abstract

PURPOSE:To compensate for the characteristics of optical displacement gages in calibration with out making an apparatus large and expensive and to make it possible to measure the thickness of a plate accurately by correcting the distance between each optical displacement gage and a body under measurement in reference to a linearity correcting table. CONSTITUTION:For example, when linearity is corrected, a calibrating plate 28 is turned with a rotary solenoid 30. As a result, the tip of the calibrating plate 28 is arranged between facing optical displacement gages 18. After the arrangement, the calibrating plate 28 is oscillated in the horizontal direction with the rotary solenoid 30. The outputs are obtained from the optical displacement gages 18 at every change of the upper and lower positions. The outputs indicate the distances between the optical displacement gages 18 and the calibrating plate 28. For example, 16 measurements are performed at every pitch, and the average value is made to be the distance datum. The average of the outputs of the optical displacement gages 18 obtained in this way is made to correspond to the expected upper and lower positions of the optical displacement gages 18. Namely, the outputs of the optical displacement gages 18 are stored in a memory 36 as a linearity correcting table. Then, the distance between each optical displacement gage 18 and a body under measurement is corrected in reference to the linearity correcting table, and the thickness of the plate is measured.

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, automatic plate thickness measuring devices have been known that automatically measure the plate thickness of a measured object transported by a transport line using an optical displacement meter.

The conventionally used apparatus is a one-point measurement apparatus using a so-called C-shaped frame, and is used to measure an object having a constant width, 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 the object to be measured with a light beam, which is a laser beam, and measures the thickness of the object. Conventionally, such devices have been used to automatically measure the thickness of objects to be measured, such as steel plates.

By the way, in general, calibration is required to ensure the accuracy of an automatic plate thickness measuring device. Calibration is performed each time the device is used, and is an essential task for device operation. More specifically, it corrects errors caused by aging of the optical displacement meter (electrical correction 1E), and corrects mechanical distortion (mechanical correction).
This is to maintain reliability and ensure accurate plate thickness 71111.

[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 changes in characteristics of the optical displacement meter.

That is, the detection characteristics of the optical displacement meter change due to environmental factors such as temperature, humidity, and similar factors such as changes over time. For example, as shown in FIG. 11, the initial characteristics shown by the solid line change to the characteristics shown by the broken line. This change causes errors in plate thickness measurements.

Several proposals have been made to eliminate such causes of error occurrence.

For example, Japanese Patent Publication No. 1-31.3705 discloses a configuration for compensating for temperature distortion occurring in the displacement meter main body case and supporting metal fittings. It shows how to insert it in the middle.

However, in such conventional proposals, the device configuration becomes large and the structure becomes complicated, resulting in a problem that the device becomes expensive.

The present invention was made with the aim of solving these problems, and it is possible to compensate for changes in the characteristics of an optical displacement meter during calibration to make it more accurate without making the device larger or more expensive. The purpose is to make it possible to measure plate thickness.

[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 a plurality of pairs of optical displacement meters that irradiate the object to be measured with a light beam and determine the distance to the object based on the reflected light, and an L-shaped bend at the tip,
A calibration plate with a predetermined thickness whose tip is placed outside the measurement area of the optical displacement meter when measuring the plate thickness of the object to be measured, and a calibration plate whose tip is positioned at a predetermined position that blocks the light beam emitted from the optical displacement meter during calibration. A rotating means for rotating the plate is used, and during measurement, the optical displacement meter is controlled to a lower position so that it is at a position determined according to the plate thickness standard of the object to be measured, and during linearity calibration, the optical displacement meter is vertical position control means for moving the optical displacement meter at a predetermined pitch in the vertical direction; horizontal position control means for controlling the left and right positions of the optical displacement meter so as to draw a predetermined trajectory during measurement; and the optical displacement meter for linearity calibration. linearity correction means for creating a linearity correction table that associates the output of the optical displacement meter with the expected 1-lower position of the optical displacement meter; , a plate thickness calculating means for calculating and averaging the plate thickness of the object to be measured based on the vertical movement amount of the optical displacement meter, the corrected distance, and the reference distance.

[Function] In the automatic plate thickness measuring device of the present invention, the distance between the optical displacement rod 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 measure the thickness of the object to be measured. The board thickness is required.

These distances between the optical displacement angle and the object to be measured are corrected using a 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 measurement values unless this change is compensated for. Therefore, in the present invention, linearity correction is performed. The linearity correction is performed while moving the optical displacement meter at a predetermined pitch in the 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 i'1l11 regular holiday. 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.

Furthermore, in the present invention, the vertical position control means is shared during measurement and calibration. Therefore, in the present invention,
The accuracy of measurement is improved without increasing the size and cost of the device compared to conventional methods.

[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
A line sensor 16 and an optical displacement meter 18 are provided on the upstream side and the optical displacement meter 18, respectively.

A pair of line sensors 16 are provided on both the upper and lower concave mounts 14, and detect the positions of both left and right ends of the tip of the object 10 to be measured. 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 gate-shaped mount 14. This optical displacement meter 18 is a device that determines the plate thickness fl11 of the regular holiday 10 to be covered. That is, the optical displacement meter 18 irradiates the measured object 10 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 actual configuration of this embodiment as a front view.

In this figure, there are two linear motor rails 20, upper and lower.
It is 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 of the 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 a pulse stage 22 1, and during measurement, the vertical positions are moved to predetermined positions by the control of the pulse stage 22 according to the plate thickness standard of the non-measuring object 10, for example, The distance is set to 133 mm from the surface of the measurement object 10. Note that providing the pulse stage 22 only on the upper side is because
This is because the lower surface of the object to be measured 10 is supported by the rollers of the conveyance line 12.

Furthermore, first and second edge sensors 24 and 26 are attached to two pairs on the left and right sides of the three pairs of optical displacement meters 18. 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. 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 1.8, and FIG. 3(b) shows the side.

In this figure, the calibration plate 28 is shown to be rotatably arranged at the position indicated by the broken line during normal plate thickness measurement and at the position indicated by the 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, in the rotary solenoid 30, the calibration plate 28 is vibrated in the horizontal direction with an amplitude of, for example, ±3 mm by a motor (not shown) or the like.

FIG. 4 shows the circuit configuration of this embodiment.

In this figure, on the one hand, the plate 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 linear motor 32 and the pulse An arithmetic control unit 34 that controls the stage 22 is shown. Furthermore, the calculation control section 34 also controls the rotary solenoid 30. In addition, this figure also shows a memory 36 that stores a reference distance determined during calibration and a linearity correction table according to a feature of the present invention. In addition, the optical displacement meter 18, the line sensor 16,
The first edge sensor 24, the second edge sensor 26, the linear motor 32, the pulse stage 22, and the rotary lenoid 30 are actually plural, or are omitted in this figure for the sake of simplicity.

Next, the operation of this embodiment will be explained.

In this embodiment, first, the object to be measured 10 is placed on the transport line 12. The mounted object 10 is
2 and reaches below the line sensor 16.

Then, the line sensor 16 detects the light-blocking position due to the object to be measured]0. i.e. line sensor]
6 detects the portion where the light beam is blocked by the object to be measured 10 and supplies this to the calculation control section 34 as the left and right end positions of the object to be measured 10 .

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, the object to be measured [0] is further transported and reaches the first edge sensor 24, whereupon the position of the optical displacement meter 18 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, the second edge sensor 26 captures both left and right sides of the object to be measured 10 . 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 trajectory of the optical displacement meter 18, and FIG. 6 shows the points (measurement positions) of this trajectory used for calculating the plate thickness.

In this embodiment, the outputs of the optical displacement meter 1-8 related to the trajectory indicated by the three arrow lines in FIG. 5 are 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 lθ reaches the line sensor roller.
The conveyance speed of the object to be measured 10 is determined from the time taken to reach the speed of 4. Since the distance between the line sensor 16 and the first edge sensor 24 is determined in advance, the time can be converted into position coordinates with reference to object to be measured 0 using this conveyance speed. Based on this conversion result, the measurement position is determined.

The measurement position is, for example, 15 m from both left and right ends of the object to be measured 10.
m line, 15mm line from both front and back ends, and center line total 6
Determine from the line of the book. That is, the intersections of these lines are set at measurement positions P-P9.

Next, for the measurement positions P□ 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 already been collected.

FIG. 7 shows the principle of plate thickness measurement in this embodiment.

In this embodiment, the thickness of the object to be measured 10 is determined based on the distance between the opposing optical displacement meters 18 during the thickness measurement 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 L2 measured by the lower optical displacement meter 18
Therefore, the plate thickness can be calculated using the following formula.

L=(Lo×L3)−(L1+L2) In this way, in this example, the measurement positions P1 to P9
Multi-point measurement of plate thickness is performed based on .

Further, in this embodiment, the distance L□ used for measuring the plate thickness is 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. 11, the solid line shows the initial characteristic, and the broken line shows the changed characteristic. Such a characteristic change appears as an error in aj regular timing.

Therefore, in this embodiment, linearity calibration is performed as the calibration.

Furthermore, 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, the gantry calibration is performed on the optical displacement meter 18 after the linearity calibration has been performed.

First, during linearity correction, the calibration plate 28 is rotated by the rotary lens 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 a rotary solenoid 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 vertically at a predetermined pitch. That is, the pulse stage 22 is controlled by the calculation control unit 34, and the vertical position of the upper optical displacement meter 18 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. For example, 16 measurements are performed for each pitch, and the average value is used as distance data. Further, the vertical movement of the optical displacement meter 18 is performed by a predetermined number of pitches, for example, a number of pitches corresponding to ±20 mm.

The average of the optical displacement meter 18 outputs obtained as in 1. (hereinafter referred to as
(simply referred to as the optical displacement meter 18 output) is associated with the expected vertical position of the optical displacement meter 18. 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. 8 shows an example of a linearity correction table.

As shown in this figure, the linearity correction table associates the control amount (command value) L3Si of the pulse stage 22 by the calculation control unit 34 with the actual optical displacement meter 18 output 3Ai. The command value L38 is a value issued based on the initial characteristics of the optical displacement meter 18, and is the vertical position that would be obtained if the characteristics of the optical displacement meter 18 had not changed, that 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 positions 18 in order to accommodate changes in the characteristics of the optical displacement meter 18.

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

That is, as shown in FIG. 9, three optical displacement meters 1
The movable range of 8 is 100-1.1.00-2 and 1.00
-3 (for example, about 40 mm), and covers the entire width 110 of the conveyance line 12. Optical displacement meter 18
The calibration plates 28 and 28 are integrally moved at predetermined intervals within their respective movable ranges]00, and a calibration table is created for each optical displacement meter 18.

FIG. 10 shows an example of a calibration table.

As shown in this figure, the calibration table is based on the horizontal position XA of the optical displacement meter and the actual reference distance at each left and right position XA. This is a table that associates A□ with .

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 ρ. , 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 ρ2, respectively.

In this case, as shown in FIG. 3, for the reference pressure rff11L □, the following formula %
The formula % holds true. Therefore, the actual reference distance Lo can be 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 the reference distance Lo is treated as the same, the accuracy of the reference distance Lo will be further improved.

This standard distance. are obtained as N pigs LoAi by moving the upper optical displacement meter 18 left and right at predetermined intervals. Note that this horizontal movement is performed by the linear motor 32 under the control of the arithmetic control section 34.

] 9 When the reference distance LoA obtained in this manner is associated with the left and right positions of the optical displacement meter 18, a calibration table as shown in FIG. 10 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]0, the calculation control unit B4 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, as shown in FIG. Therefore, by determining the difference between this data and the command value, it is possible to determine the error caused by the characteristic change included in the current output of the optical displacement meter 18. By subtracting this error from the output of the optical displacement meter 18, the influence of errors caused by changes in the characteristics of the optical displacement meter 18 can be eliminated.

Also, the reference distance used when calculating plate thickness.

In order to make the correction, the arithmetic 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 based on the reference distance related to the left and right positions. As described above, this reference distance is a value that reflects the distortion of the pedestal, so if the plate thickness is calculated using this reference pressure MLo, errors that occur when the pedestal 14 is distorted can be prevented. .

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 8 and the object 41 is determined as a spatial average of several points in the vicinity of the measurement point, and as a result, variations in the surface texture between multiple objects 10 and the same object Even when there are variations in the surface texture of the measuring object 10, the influence of this surface texture can be corrected.1. This allows for more accurate plate thickness measurements.

Furthermore, the pulse stage 22 can be used both during measurement and during linearity calibration, and the configuration related to calibration can be realized with a small and inexpensive device.

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 is created and the optical displacement meter output is corrected using this linearity correction table, so that more accurate plate thickness measurement is possible. become. Further, since the vertical position control means is used for both measurement and calibration, such effects can be obtained with a small and inexpensive device.

[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 plate thickness measurement principle, Figure 8 is a diagram showing a linearity correction table, Figure 9 is a diagram showing the movement range of the optical displacement meter, Figure 10 is a diagram showing the calibration table, and Figure 11 is a diagram showing the movement range of the optical displacement meter. The figure is a diagram showing the characteristics of the optical displacement meter. 10 ... Measured object 12 ... Transport line 18 ... Optical displacement meter 28 ... Calibration plate 30 ... Rotary solenoid 32 ... Linear motor 34 ... Arithmetic 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; Vertical position control means that controls the vertical position of the optical displacement meter so that it is at a predetermined position, moves the optical displacement meter vertically at a predetermined pitch during linearity calibration, and draws a predetermined trajectory on the object to be measured during measurement. lateral position control means for controlling the left and right positions of the optical displacement meter, and linearity correction means for creating a linearity correction table that associates the output of the optical displacement meter with the expected vertical position of the optical displacement meter during linearity calibration. , Correct the distance between the optical displacement meter and the object to be measured by referring to the linearity correction table, and calculate the thickness of the object to be measured based on the vertical movement amount of the optical displacement meter, the corrected distance, and the reference distance. An automatic plate thickness measuring device comprising: averaging plate thickness calculation means.