JP2675662B2 - Automatic plate thickness measuring device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic thickness measuring apparatus for automatically measuring the thickness of an object to be transported by a transport line in a non-contact manner by reflection of a light beam.

[Prior Art] Conventionally, there has been known an automatic plate thickness measuring device for automatically measuring a plate thickness of an object to be measured conveyed by a conveying line by an optical displacement meter.

An apparatus used in the related art is a one-point measuring apparatus using a so-called C-shaped frame, and measures an object having a constant width, that is, an object having a fixed width.

In this apparatus, optical displacement meters are arranged above and below a transport line. The object to be measured is irradiated with a light beam as a laser beam by the optical displacement meter, and the thickness of the object to be measured is measured. Conventionally, such a device has been used to automatically measure the plate thickness of a steel plate or the like to be measured.

By the way, generally, calibration is necessary to ensure the accuracy of the automatic plate thickness measuring device. Calibration is performed every time the device is used, and it is an essential work for operating the device. More specifically, the error due to aging of the optical displacement meter is corrected (electrical correction), and the mechanical distortion is corrected (mechanical correction).
It is intended to maintain reliability and accurately measure the plate thickness.

[Problems to be Solved by the Invention] However, conventionally, there has been a problem that an error occurs in the plate thickness measurement due to a characteristic change of the optical displacement meter.

That is, the detection characteristic of the optical displacement meter changes due to environmental factors such as temperature, humidity, etc., and similar factors due to aging. For example, as shown in FIG. 11, the initial characteristic indicated by the solid line changes to the characteristic indicated by the broken line. This change causes an error in the plate thickness measurement.

Several proposals have been made to eliminate such a cause of error.

For example, Japanese Examined Patent Publication (Kokoku) No. 1-313705 discloses a configuration for compensating for temperature distortion occurring in a displacement gauge main body case and a support fitting.
That is, a method of inserting the linear thermal expansion coefficient compensating member between the main body case and the support fitting or in the middle of the support fitting is shown.

However, in such a conventional proposal, there is a problem that the size of the device becomes large and the structure becomes complicated, so that the cost of the device becomes high.

The present invention has been made to solve such a problem, and it is possible to compensate for a characteristic change of an optical displacement meter at the time of calibration without increasing the size of the device or increasing the price, and thus to achieve a more accurate measurement. The purpose is to enable plate thickness measurement.

[Means for Solving the Problem] In order to achieve such an object, the present invention forms a pair on a pedestal above and below a transportation line for transporting an object to be measured with a predetermined reference distance. A plurality of pairs of optical displacement gauges that are arranged and determine the distance to the object to be measured based on the reflected light by irradiating the object to be measured with a light beam, and the tip has an L-shaped bend, and the plate thickness of the object to be measured. During measurement, the tip is located outside the measurement range of the optical displacement meter, and the calibration plate is rotated so that the tip is positioned at a predetermined position that blocks the light beam emitted from the optical displacement meter during calibration. The rotating means and the vertical position of the optical displacement meter are controlled so that the position is determined according to the plate thickness standard of the object to be measured during measurement.
Vertical position control means for moving the optical displacement meter in the vertical direction at a predetermined pitch, horizontal position control means for controlling the horizontal position of the optical displacement meter so as to draw a predetermined trajectory on the measured object during measurement, and for linearity calibration 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, and corrects the distance between the optical displacement meter and the measured object by referring to the linearity correction table. And 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.

[Operation] In the automatic plate thickness measuring device of the present invention, based on the distance between the optical displacement meter and the measured object, the vertical movement amount of the optical displacement meter, and the reference distance between the opposed optical displacement meters, The plate thickness is required.

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

For example, when the characteristics of the optical displacement meter change from the initial characteristics, an error will occur in the plate thickness measurement value unless this change is compensated. Therefore, linearity correction is performed in the present invention. The linearity correction is performed while moving in the vertical direction at a predetermined pitch, 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. The expected vertical position is the vertical position obtained by position control based on the initial characteristics of the optical displacement meter, for example.

A table showing the correspondence between the output of the optical displacement meter and the vertical position will be called 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. As a result, the error caused by the above-mentioned characteristic change depending on the vertical position of the optical displacement meter at the time of measurement is compensated.

Further, 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 of the device structure and thus increasing the price, as compared with the related art.

EXAMPLES Hereinafter, preferred examples of the present invention will be described with reference to the drawings.

FIG. 1 shows the actual configuration of an automatic thickness measuring apparatus according to one embodiment of the present invention. In particular, FIG. 1 (a) shows the appearance of the apparatus viewed from above, and FIG. 1 (b) shows the appearance of the apparatus viewed from the side.

In this figure, a transport line 12 that transports the measured object 10 in a direction indicated by an arrow in the figure is shown. The measured object 10 in this figure is a steel sheet having different thicknesses, widths, and the like, and three figures 10-1, 10-2, and 10-3 are shown in the figure. In this embodiment, the measuring object 10 to be measured for the thickness is, for example, a thickness of 4 to 60 mm, a width of 800 to 4000 mm and a length of 150 mm.
It has a standard of 0 to 14000 mm, and is arranged at an arbitrary position on the transport line 12 in an arbitrary posture.

In addition, a pair of upper and lower portal frames 14 are provided so as to straddle the transport line 12. A line sensor 16 is provided on the upstream side of the transport line 12 of the portal frame 14, and an optical displacement meter 18 is provided on the downstream side.

The line sensors 16 are provided on the upper and lower gate-shaped pedestals 14 so as to form a pair, and detect the left and right end positions of the tip of the DUT 10. The left and right end positions detected are the optical displacement meter 18
Is used for the initial setting of the position.

Further, three pairs of the optical displacement meters 18 are movably provided on the gate mount 14. The optical displacement meter 18 is a device for measuring the thickness of the measured object 10. That is, the optical displacement meter 18 is the object to be measured 10
It irradiates a light beam on and captures the reflected light. further,
The distance to the object to be measured 10 is calculated based on the captured reflected light, and is used for plate thickness calculation based on the principle described later.

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

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

The upper three of the optical displacement meters 18 are attached to the pulse stage 22. That is, the three optical displacement gauges 18 are driven in the vertical direction by the pulse stage 22, and the vertical position is set to a predetermined position by the control of the pulse stage 22 according to the plate thickness standard of the non-measuring body 10 during measurement, for example, to be measured. It is set to 133 mm from the body 10 surface. The pulse stage 22 is provided only on the upper side because the lower surface of the measured object 10 is supported by the rollers of the transfer line 12.

Further, 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, respectively. 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 measured object 10.

FIG. 3 shows an apparatus configuration for calibrating 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.
Each is shown.

In this drawing, the calibration plate 28 which is pivotally disposed at a position as shown by a broken line during normal thickness measurement and at a position as shown by a solid line during calibration is shown. 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 verified. The rotation of the calibration plate 28 is performed by a rotary solenoid 30. Further, the rotary solenoid 30 is
The calibration plate 28 vibrates horizontally with an amplitude of, for example, ± 3 mm by a motor or the like (not shown).

 FIG. 4 shows a circuit configuration of this embodiment.

In this figure, the plate thickness of the object to be measured 10 is calculated based on the output of the optical displacement meter 18 on the one hand, and the linear motor 32 and the pulse stage based on the outputs of the line sensor 16 and the first and second edge sensors 24 and 26 on the other hand. Calculation control unit 34 for controlling 22
It is shown. Further, the arithmetic control unit 34 also controls the rotary solenoid 30. In addition, this drawing also shows a memory 36 that stores a reference distance required during calibration and a linearity correction table according to the features of the present invention. The optical displacement meter 18, the line sensor 16, the first edge sensor 24, the second
The edge sensor 26, the linear motor 32, the pulse stage 22, and the rotary solenoid 30 are actually plural, but are omitted in this drawing for simplification of the drawing.

 Next, the operation of this embodiment will be described.

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

Then, the light-shielded position by the measured object 10 is detected by the line sensor 16. That is, the line sensor 16
Detects a portion where the light beam is blocked by the measured object 10 and supplies the detected portion as the left and right end positions of the measured object 10 to the arithmetic and control unit 34.

The arithmetic control unit 34 controls the drive of the linear motor 32 based on the output of the line sensor 16 to control the position of the optical displacement meter 18. Specifically, the pair of optical displacement meters 18 on each of the left and right sides is moved to both left and right positions of the measured object 10 detected as the light shielding position, and the pair of optical displacement meters 18 disposed at the center is moved to the left and right. Is maintained at the central position of the optical displacement meter 18. Thereby, the position of the optical displacement meter 18 is initialized.

Thereafter, when the measured object 10 is further transported and reaches the first edge sensor 24, the position of the optical displacement meter 18 is finely adjusted by the first edge sensor 24. That is, the arithmetic control unit 34 controls the linear motor 32 according to the output of the first edge sensor 24.

Next, the left and right ends of the measured object 10 are captured by the second edge sensor 26. At this time, the arithmetic control unit 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, by this control, the second edge sensor 26 continues to capture the right and left ends of the measured object 10 and the optical displacement meters 18 at the left and right ends. Means to detect and scan a locus having a predetermined distance from both left and right ends of the object to be measured 10.

FIG. 5 shows the light beam trajectory of the optical displacement meter 18, and FIG. 6 shows points (measurement positions) used in the thickness calculation of the trajectory.

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

More specifically, the arithmetic and control unit 34 determines the transport speed of the measured object 10 from the time from when the tip of the measured object 10 reaches the line sensor 16 to when it reaches the first edge sensor 24.
Since the distance between the line sensor 16 and the first edge sensor 24 is determined in advance, the transport speed is used to determine the time.
Can be converted into position coordinates. The measurement position is determined based on the conversion result.

The measurement position is determined, for example, from a total of six lines, which are a line of 15 mm from both left and right ends of the object to be measured 10, a line of 15 mm from both front and rear ends, and a center line. That is, the intersection of these lines is measured at the measurement position P ₁
Set to ~P _9.

Next, the measurement position P ₁ to P ₉ which is set in this manner, the plate thickness calculation based on the optical displacement meter 18 output that has already been collected is performed by the arithmetic control unit 34.

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

In this embodiment, the plate thickness of the object 10 to be measured is obtained based on the distance between the optical displacement gauges 18 facing each other during the plate thickness measurement and the above-mentioned spatial average.

First, it is assumed the optical displacement meter 18 facing distance in the state object to be measured 10 is not, i.e. the reference distance L ₀ is determined designed to. In the case of the measured object 10 having a plate thickness L, the optical displacement meter 18
The amount of expanding the sense of, that is, the moving amount L ₃ of the optical displacement meter 18 is set.

Then, the distance L ₁ measured by the upper optical displacement meter 18
And from the distance L ₂ measured by the lower optical displacement meter 18,
The plate thickness L is determined by the following equation.

_{L = (L 0 + L 3} ) - (L 1 + L 2) Thus, in the present embodiment, the multi-point measurement of the thickness L based on the measurement position P ₁ to P ₉ are executed.

Further, the distance L ₁ used for measuring the plate thickness L in this embodiment is a value corrected by the linearity correction table created for each optical displacement meter 18 at the time of calibration.

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

The optical displacement meter 18 is a device that is accompanied by characteristic changes due to environmental factors, changes over time, and the like. In FIG. 11, the solid line shows the initial characteristics, and the broken line shows the changed characteristics.
Such characteristic changes will appear as an error during measurement. Therefore, in the present embodiment, linearity calibration is performed as the calibration.

When the gantry 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. Therefore, in this embodiment, the gantry 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 is performed.

First, when correcting the linearity, 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 formed of a white ceramic plate having a known plate thickness, and is oscillated in the horizontal direction by the rotary solenoid 30 after the placement. This vibration is a vibration with an amplitude of about ± 3 mm, and 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 with a predetermined pitch. That is, the pulse stage 22 is controlled by the arithmetic 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 is an optical displacement meter
It shows the distance between 18 and the calibration plate 28. For example, the measurement is performed 16 times for each pitch, and the average value is used as the distance data. Further, the vertical displacement of the optical displacement meter 18 is executed by a predetermined pitch number, for example, a pitch number corresponding to ± 20 mm.

The average of the outputs of the optical displacement meter 18 thus obtained (hereinafter, simply referred to as the output of the optical displacement meter 18) is associated with the expected vertical position of the optical displacement meter 18. That is, the optical displacement meter
The 18 outputs are stored in the memory 36 as a linearity correction table associated with the expected vertical position.

FIG. 8 shows an example of the linearity correction table.

As shown in this figure, the linearity correction table is a control amount (command value) of the pulse stage 22 by the arithmetic control unit 34.
The L 3 _Si is _associated with the actual optical displacement meter 18 output L _3Ai . The command value L _3Si is a value that is 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 were not changed, that is, an ideal value.
Therefore, the linearity correction table associates the ideal value and the actual value with respect to the characteristics of the optical displacement meter 18.

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

In this way, the gantry calibration is performed after the linearity calibration is performed. In this gantry calibration, the upper and lower optical displacement meters 18 and the calibration plate 28 are horizontally moved integrally.

That is, as shown in FIG. 9, three optical displacement meters
The movable range of 18 is a range such as 100-1, 100-2 and 100-3 (for example, about 40 mm), and the entire width of the transfer line 12 is 11
It covers 0. The optical displacement meter 18 and the calibration plate 28 are integrally moved at a predetermined interval within each movable range 100, and a calibration table is created for each optical displacement meter 18.

 FIG. 10 shows an example of the calibration table.

As shown in this figure, the calibration table is a table that associates the left-right position x _Ai of the optical displacement meter with the actual reference distance L _{0Ai at} each left-right position x _Ai .

In the frame calibration, the calibration plate is used as in the linearity calibration.
28 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 plate thickness of the calibration plate 28 is l ₀ , the distance from the upper and lower optical displacement meters 18 to the calibration plate 28 (that is, the upper and lower optical displacement meters).
18 outputs) are designated as l ₁ and l ₂ , respectively. In this case, as shown in FIG. 3, the following formula L ₀ = l ₁ + l ₂ + l ₀ holds for the reference distance L ₀ . Therefore, the calculation control unit 34 by executing a calculation based on the above equation, so that the actual reference distance L ₀ is obtained. Moreover, such calculation is performed a predetermined number of times
The accuracy of the reference distance L ₀ is further improved by calculating the average 16 times and treating this average value as the reference distance L ₀ .

The reference distance L ₀ is obtained as N pieces of data L _0Ai by moving the upper optical displacement meter 18 left and right at a predetermined interval. The horizontal movement is performed by the linear motor 32 under the control of the arithmetic control unit 34.

The reference distance L _0Ai thus obtained is the optical displacement meter 18
When associated with the left and right positions of, a calibration table as shown in FIG. 10 is created. The calibration table is created for each pair of optical displacement meters 18.

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

At the time of measurement, these linearity correction table and calibration table are referred to.

That is, when determining the plate thickness of the object to be measured 10, the calculation control unit
34 reads the 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 _3Ai in FIG. Therefore, if the difference between this data and the command value is obtained, the error due to the characteristic change contained in the current output of the optical displacement meter 18 can be obtained. If this error is subtracted from the output of the displacement meter 18, the influence of the error due to the characteristic change of the optical displacement meter 18 is eliminated.

Further, in order to correct the reference distance used in the plate thickness calculation by L ₀ , the calculation control unit 34 reads the data related to the calibration table from the memory 36 based on the lateral position of the optical displacement meter 18. The read data is the reference distance L ₀ related to the left and right positions. Since the reference distance L ₀ is a value that reflects the pedestal distortion as described above, the plate thickness calculation using this reference distance L ₀ prevents the occurrence of an error when the gantry 14 is distorted.

As described above, according to the present embodiment, the calibration plate 28 can collectively perform the electrical correction and the mechanical correction by a simple means. Further, the linearity correction table and the calibration table can be used for correction, and the plate thickness L
Can be calculated to ensure accuracy and reliability.

Further, the distance between the optical displacement meter 18 and the measured object 10 is obtained as a spatial average in the vicinity of the measurement point, and as a result, a plurality of measured objects are measured.
Even if there is a variation in the surface texture between 10 and a variation in the surface texture in the same measured object 10, it is possible to correct the influence of this surface texture and measure the plate thickness L more accurately.

Further, the pulse stage 22 can be shared between the measurement and the linearity calibration, and the configuration related to the calibration can be realized by a small and inexpensive device.

Although the pulse stage 22 is provided only on the upper side in the above description, it may be provided on the lower side. in this case,
A linearity correction table is created for the upper and lower optical displacement meters 18 to enable more precise measurement.

[Effects of the Invention] As described above, according to the present invention, since the linearity correction table is created and the output of the optical displacement meter is corrected by this linearity correction table, more accurate plate thickness measurement is possible. become. Moreover, since the vertical position control means is used for both measurement and calibration, such an effect can be obtained with an inexpensive and compact device.

[Brief description of the 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. FIG. 1 (a) is a top view, FIG. 1 (b) is a side view, and FIG. FIG. 3 is a front view showing a more detailed substance structure of this embodiment, FIG. 3 is a schematic view showing the structure of the calibration means of this embodiment, and FIG. 3 (a) is a front view and FIG. 3 (b). ) Is a side view, FIG. 4 is a block diagram showing a circuit configuration of this embodiment, FIG. 5 is a diagram showing a trajectory of a light beam emitted from an optical displacement meter, FIG. 6 is a diagram showing a plate thickness measurement position, FIG. 7 is a diagram showing a plate thickness measuring principle, FIG. 8 is a diagram showing a linearity correction table, FIG. 9 is a diagram showing a moving range of an optical displacement meter, FIG. 10 is a diagram showing a calibration table, and FIG. The figure shows the characteristics of the optical displacement meter. 10: Object to be measured 12: Transport line 18: Optical displacement meter 28: Calibration plate 30: Rotary solenoid 32: Linear motor 34: Arithmetic control unit

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shuji Naito 1-1 Tobahata-cho, Tobata-ku, Kitakyushu, Fukuoka Prefecture Inside the Yawata Works (72), Nippon Steel Co., Ltd. No. 1-1 Machi Nippon Steel Co., Ltd. Hachiman Works (72) Inventor Hideki Oguchi 5-1-1 Shimorenjaku, Mitaka City, Tokyo Nihon Radio Co., Ltd. (72) Inventor Kazuhiko Asakawa Mitaka City, Tokyo Shimorenjaku 5-1-1, Nihon Radio Co., Ltd. (72) Koichi Itohara 5-1-1 Shimorenjaku, Mitaka-shi, Tokyo Nihon Radio Co., Ltd. (72) Inventor Fumio Murakami 5 Shimorenjaku, Mitaka-shi, Tokyo (1-1) Nihon Radio Co., Ltd. (72) Inventor Hideki Uehara 5-1-1, Shimorenjaku, Mitaka City, Tokyo Nihon Radio Co., Ltd. (56) References 1-2221605 (JP, A) JP-A-4-116407 (JP, A) JP-A-4-116408 (JP, A) JP-A-3-51706 (JP, A) Actual Development Sho 59-41711 (JP, U) Showa 57-16905 (JP, U) Japanese Patent Publication 7-76687 (JP, B2) Japanese Patent Publication 7-76688 (JP, B2) Japanese Publication 6-82046 (JP, B2) Japanese Publication 6 -82047 (JP, B2)

Claims (1)

(57) [Claims] 1. A pair of units are arranged on a pedestal above and below a conveyance line for conveying an object to be measured, and are arranged at a predetermined reference distance. A plurality of pairs of optical displacement gages for obtaining the distance to the measurement object, and a tip with an L-shaped bend, of which the tip is placed outside the measurement range of the optical displacement gage when measuring the thickness of the object to be measured. Calibration plate, rotation means for rotating the calibration plate so that the tip is located at a predetermined position that blocks the light beam emitted from the optical displacement meter during calibration, and during measurement, set according to the plate thickness standard of the DUT. The vertical position of the optical displacement meter is controlled so that it can be moved to a desired position, and during linearity calibration, the vertical position control means that moves the optical displacement meter in the vertical direction at a specified pitch, and draws a specified trajectory on the measured object during measurement. Left and right position control means for controlling the left and right position of the optical displacement meter, 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 at the time of calibration, and the optical displacement meter and the object to be measured by referring to the linearity correction table. And a plate thickness calculating means for calculating the average of the plate thickness of the object to be measured based on the vertical displacement of the optical displacement meter, the corrected distance and the reference distance, and an automatic plate characterized by the following: Thickness measuring device.