JP2728555B2 - Automatic thickness gauge - 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] An automatic thickness measuring apparatus for automatically measuring the thickness of an object to be measured conveyed by a conveyance line using an optical displacement meter has been conventionally known.

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 thickness of an object to be measured such as a steel plate.

[Problems to be Solved by the Invention] However, such a device has a problem that light beams emitted from upper and lower optical displacement meters interfere with each other.

That is, the thickness measurement using the light beam is based on a method in which the optical displacement meters that irradiate the light beam from above and below the object to be measured separately obtain the distance from the object to be measured. Therefore, if the light beams interfere with each other, it becomes difficult to accurately measure the thickness.

In order to prevent such difficulties, it is sufficient that the area of the measured object is sufficiently large. The energy of the light beam is approximately Gaussian distributed. Therefore, the thickness measurement requires an area of the object to be measured which is about 10 times the beam diameter of the light beam. Conversely, this means that only an object having a large shape can be used for automatic thickness measurement.

As means for preventing light beam interference, Japanese Patent Laid-Open No.
As disclosed in Japanese Patent No. 235806, there is another means for emitting a light beam only at the time of measurement. When this means is employed, interference between light beams by the upper and lower optical displacement meters can be prevented by setting the light emission timing. But,
In this case, it takes time to stabilize the operation of the optical displacement meter, and it is difficult to measure the plate thickness at high speed.

On the other hand, when performing automatic plate thickness measurement, it is necessary to perform calibration periodically. This corrects errors due to aging of the optical displacement meter (electrical correction), and corrects mechanical distortion (mechanical correction) to maintain reliability and ensure accurate thickness measurement. Things.

However, there are various problems in such a calibration, and a solution is desired.

Specifically, for example, there is a problem that it is necessary to remove the optical displacement meter at the time of electrical correction, and it is necessary to use a dedicated jig. Another problem is that a special measuring device is required for mechanical correction. further,
In common to both, the transportation line must be stopped, resulting in economic loss, the need for large-scale work and the need for calibration specialists,
There are problems such as high price.

Conventionally, several proposals have been made to solve such a problem. For example, JP-A 1-2216
As described in Japanese Patent Publication No. 05 or No. Sho 59-41711, the reference DUT is disposed at a plane position having substantially the same height as the DUT, and the reference DUT is intermittently interposed. There are a method of correcting the reference point by measuring the thickness, and a method of putting a calibration plate having a predetermined thickness into and out of the passband of the light beam emitted from each of the pair of optical displacement meters.

However, these methods are premised on one-point measurement using a C-shaped frame, and are difficult to apply, for example, when performing accurate and precise thickness measurement by multipoint measurement.
This is because in the case of multipoint measurement, it is necessary to perform calibration over the entire width of the transport line, and the above-described method is a method of performing calibration at one point.

An object of the present invention is to solve such a problem, and provides an automatic thickness measuring apparatus capable of performing calibration with a simple and inexpensive small apparatus in the case of multipoint measurement. The purpose is to do. Another object of the present invention is to provide an automatic thickness measuring apparatus capable of performing high-speed calibration using a small non-transmissive calibration plate by eliminating interference of a light beam at the time of calibration. I do.

[Means for Solving the Problems] In order to achieve such an object, the present invention is arranged above and below a transport line for transporting an object to be measured and arranged at a predetermined reference distance apart from each other, A plurality of pairs of optical displacement meters that irradiate a light beam to a measured object to determine a distance to the measured object based on reflected light, and a thickness of the measured object based on a distance measured by the optical displacement meter and a reference distance. Thickness calculating means for calculating; absent detecting means for detecting that the object to be measured is not being conveyed by the conveying line; and a tip having an L-shaped bend, and the tip being displaced when measuring the thickness of the object to be measured. The calibration plate having a predetermined thickness placed outside the measurement area of the meter, and the tip is located at a predetermined position that blocks a light beam emitted from the optical displacement meter when it is detected that the object to be measured is not being conveyed. The rotation means for rotating the calibration plate and the calibration plate Alternate irradiation stopping means for alternately stopping light beam irradiation from each of the upper and lower optical displacement meters when at a position where the light beam emitted from the optical displacement meter is interrupted, and a plate for the output of the optical displacement meter and a calibration plate during calibration Reference distance calculating means for obtaining a reference distance based on the thickness.

[Operation] In the automatic thickness measuring apparatus of the present invention, when the object to be measured is conveyed by the conveying line and reaches below the optical displacement meter, the thickness of the object to be measured is reflected by the light beams emitted from the upper and lower optical displacement meters. Is calculated. This calculation is performed using the reference distance between the optical displacement meters. This measurement is performed as a multipoint measurement.

At the time of calibration, the following operation is performed. That is, in this case, the absence of the object to be measured is detected by the absence detector, and the tip of the calibration plate is rotated into the measurement area of the displacement meter. This calibration plate blocks the light beam emitted from the optical displacement meter. When the light beam is blocked, the optical displacement meter calculates the distance to the calibration plate based on the reflected light of the light beam, and further calculates the reference distance based on this distance and the thickness of the calibration plate. This reference distance is used for calculating the thickness when measuring the thickness.

In the present invention, at the time of calibration, irradiation of the light beam is stopped alternately up and down. This stop is temporary, preferably instantaneous.

Therefore, in the present invention, calibration in multipoint measurement is performed by easy means. In addition, this calibration is performed with the light beam temporarily stopped, so that a high-speed calibration can be performed using a non-transmissive calibration plate without using a large calibration plate that takes into account the diffusion of the light beam. Becomes possible.

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 both the upper and lower portal frames 14 so as to form a pair, and detect the left and right end positions of the tip of the measured object 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 provided on the portal gantry 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 irradiates the measured object 10 with a light beam and takes in the reflected light. Further, the distance to the measured object 10 is obtained based on the taken-in reflected light, and is used for a 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 meters 18 are driven by the pulse stage 22 in the vertical direction.

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 fine-tune the position of the optical displacement meter 18 that is initially set according to the output of the line sensor 16. The second edge sensor 26 is used to detect the side edge of the measured object 10 following.

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 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.

 FIG. 4 shows a circuit configuration of this embodiment.

In this figure, on the one hand, the thickness of the measured object 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 are determined based on the outputs of the line sensor 16 and the first and second edge sensors 24 and 26. Operation control unit that controls stage 22
34 is shown. The arithmetic control unit 34 is an optical displacement meter.
18 operation control is performed. Further, a memory 36 for storing a reference distance obtained at the time of calibration as a calibration table is shown. Although the optical displacement meter 18, the line sensor 16, the first edge sensor 24, the second edge sensor 26, the linear motor 32 and the pulse stage 22 are actually plural, they are omitted in this figure for simplification of the figure. I have.

 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 and control unit 34 controls the linear motor 32 according to the stress 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, the second edge sensor 26 keeps following and capturing both left and right ends of the measured object 10 by this control, and Will detect and scan a locus at a predetermined distance from both left and right ends of the measured object 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 outputs of the optical displacement meter 18 relating to the trajectory indicated by the three arrows in FIG. 5 are 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 by design, the time can be converted into position coordinates based on the measured object 10 using this transport speed. The measurement position is determined based on the conversion result.

The measurement position is determined from, for example, a total of six lines including a line of 15 mm from both left and right ends of the measured object 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 thickness measurement in this embodiment.

In this embodiment, an optical displacement meter is used for measuring the thickness of a sheet.
The plate thickness of the measured object 10 is obtained based on the distance of 18 and the output of the pair of optical displacement meters 18.

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 to expand the distance between L _3.

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.

Next, a calibration operation according to the features of the present invention will be described.

Interval serving reference distance L of the optical displacement meter 18 ₀ changes environmental factors, by aging or the like. In order to prevent an error from occurring due to this change, calibration using the above-described calibration plate 28 is necessary.

First, a calibration plate 28 having a known thickness and formed of a white ceramic plate is rotated by a rotary solenoid 30 and placed at a position between opposing optical displacement meters 18. The thickness of this calibration plate 28
l ₀ , and the distances from the upper and lower optical displacement meters 18 to the calibration plate 28 are l ₁ and l ₂ , respectively.

The distance l ₁ and l ₂ is obtained as the output of the optical displacement meter 18. On the other hand, as shown in FIG. 3, for the reference distance L ₀ , the following equation is established: L ₀ = l ₁ + l ₂ + 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.

In this embodiment, by moving the respective optical displacement meter 18 in the lateral direction, the calculation of the reference distance L ₀ is performed for the entire width of the conveying line 12.

That is, the range in which each optical displacement meter 18 can be driven by the linear motor 32 has a relationship as shown in FIG. 8, for example. Driving range 100-1, 100- of three pairs of optical displacement meters 18
2, 100-3 overlap each other, and the total width of the transport line is 110
Are covered by these driving ranges 100-1, 100-2, and 100-3.

In the present embodiment, the calculation of the reference distance L ₀ by the calibration plate 28 is
This is performed while the optical displacement meter 18 is driven by the linear motor 32.
That is, the arithmetic control unit 34 controls the linear motor 32 to drive the optical displacement meter 18 left and right. For example, each time the optical displacement meter 18 is moved by a predetermined amount, the calculation control unit 34 calculates the reference distance L ₀ based on the output l ₁ and l ₂ of the optical displacement meter 18.

The reference distance L ₀ obtained in this manner is associated with the position coordinates of the optical displacement meter 18 as shown in FIG. 9, and stored in the memory 36 as a calibration table.

This calibration table is created for each pair of the optical displacement meters 18. The calibration table is referred to when measuring the thickness of the measured object 10.

That is, the calculation control unit 34, a reference distance L ₀ to be used in the calculation of the thickness L, obtained by referring to the calibration table that is developed in the memory 36. As a result, the sheet thickness L becomes
12 Recently measured reference distance that fits in the width direction
It will be obtained based on L _0.

Further, in the present embodiment, the arithmetic control unit 34 instructs the optical displacement meter 18 to temporarily stop light beam emission during calibration.

That is, in order to prevent the light beams related to the upper and lower optical displacement meters 18 from interfering with each other, one side is temporarily stopped, and the measurement is performed on the other side.

As described above, according to the present embodiment, the calibration plate 28 can collectively perform the electrical correction and the mechanical correction by simple means, and can ensure accuracy and reliability. In addition, by creating and referring to the calibration table, it is possible to cancel variations in the optical displacement meter 18 and changes in the reference distance for each position, and perform more accurate and highly reliable thickness measurement.

In addition, since the irradiation of the calibration plate 28 with the light beam is temporarily stopped, interference between the light beams during calibration is prevented. Accordingly, it is not necessary to use a large calibration plate 28, and since this stop is temporary, high-speed plate thickness measurement can be performed without having to wait for stable operation of the optical displacement meter 18.

[Effects of the Invention] As described above, according to the present invention, in a multi-point measurement apparatus, calibration including electrical correction and mechanical correction is performed by rotating a calibration plate, and light Since the calibration is performed while the displacement meter and the calibration plate are moved together, accurate and highly reliable plate thickness measurement can be performed over the entire movable width of the optical displacement meter. Further, the device configuration required for this is easy, and is performed automatically, so that there is no need for an expert or the like, and calibration can be performed at low cost. In addition, the temporary stop control of the light beam enables calibration using a non-transmissive calibration plate without increasing the size of the calibration plate and reducing the speed of the calibration operation.

[Brief description of the drawings]

FIG. 1 is a schematic external view showing an actual configuration of an automatic thickness measuring apparatus according to one embodiment of the present invention. FIG. 1 (a) is a top view, FIG. 1 (b) is a side view, FIG. 2 is a front view showing a more detailed actual configuration of this embodiment. FIG. 3 is a schematic diagram showing the configuration of the calibration means of this embodiment. FIG. 3 (a) is a front view, and FIG. FIG. 4 (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, and FIG. FIG. 7 is a diagram showing a measurement position, FIG. 7 is a diagram showing a plate thickness measurement principle, FIG. 8 is a diagram showing a relationship of a moving range of each optical displacement meter, and FIG. 9 is a diagram showing a calibration table. 10… Measurement object 12… Transport line 16… Line sensor 18… Optical displacement meter 28… Calibration plate 30… Rotary solenoid 32 …… Linear motor 34 …… Calculation control unit 36… Memory L ₀ … … Reference distance

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Toshio Fujikawa 1-1, Hibata-cho, Tobata-ku, Kitakyushu-city, Fukuoka Prefecture Inside Nippon Steel Corporation Yawata Works (72) Inventor Hideki Oguchi 5-Shimorenjaku, Mitaka-shi, Tokyo No. 1-1 Inside Japan Radio Co., Ltd. (72) Inventor Tomohiko Ohno 5-1-1 Shimo-renjaku, Mitaka City, Tokyo Japan Inside Japan Radio Co., Ltd. No. 1 Inside Nippon Radio Co., Ltd. (72) Inventor Taichiro Yoneya 5-1-1 Shimorenjaku, Mitaka City, Tokyo Intranet Nippon Radio Co., Ltd. (72) Hiroaki Igarashi 5-1-1, Shimorenjaku, Mitaka City, Tokyo No. Japan Radio Co., Ltd. (56) References JP-A-4-60405 (JP, A) JP-A-2-302606 (JP, A) JP-A-1-221605 (JP, A) Four 1711 (JP, U)

Claims (1)

(57) [Claims] A pair is formed above and below a transport line for transporting an object to be measured and is disposed at a predetermined reference distance,
A plurality of pairs of optical displacement meters that irradiate a light beam to the measured object to determine the distance to the measured object based on the reflected light, and measure the thickness of the measured object based on the distance measured by the optical displacement meter and the reference distance. Thickness calculating means for calculating; absent detecting means for detecting that the object to be measured is not being conveyed by the transport line; an end having an L-shaped bend; A calibration plate with a predetermined thickness placed outside the measurement area of the displacement meter, and a tip located at a predetermined position to block a light beam emitted from the optical displacement meter when it is detected that the object to be measured is not being conveyed. Rotating means for rotating the calibration plate so that the light beam emitted from the optical displacement meter is stopped alternately when the calibration plate is rotated to block the light beam emitted from the optical displacement meter. Alternate irradiation stop means and light displacement during calibration Automatic gauge measuring apparatus of the reference distance calculating means for obtaining a reference distance based output and the thickness of the calibration plate, comprising: a.