WO2021186910A1

WO2021186910A1 - Thickness measurement device and thickness measurement method

Info

Publication number: WO2021186910A1
Application number: PCT/JP2021/003070
Authority: WO
Inventors: 恭隆増田
Original assignee: 横浜ゴム株式会社
Priority date: 2020-03-19
Filing date: 2021-01-28
Publication date: 2021-09-23
Also published as: JP2021148630A

Abstract

The present invention improves efficiency in measuring the thickness of an object, over a wide range.　A thickness measurement device 10 comprises: a linear array of light sources 12 that are disposed in parallel to the extension direction of an object O on the side of a first surface F1 of the object O, and that emit light toward the first surface F1; a plurality of light-receiving parts 14 that are disposed to be aligned on the side of a second surface F2 of the object O in parallel to the light sources 12 and that receive transmitted light that has been transmitted through the object O; a moving part 16 that moves the object O while maintaining the distance between the object O and the light sources 12 and the distance between the object O and the light-receiving parts 14 constant; and a thickness calculation unit 18 that calculates, on the basis of the illuminance of the transmitted light received by the respective light-receiving parts 14, the thickness at a location of the object O positioned between the light sources 12 and the light-receiving parts 14.

Description

Thickness measuring device and thickness measuring method

The present invention relates to a thickness measuring device and a thickness measuring method for measuring the thickness of an object over a predetermined range.

Conventionally, a liner arranged on the inner surface of an FRP (Fiber Reinforced Plastics) tank used for various purposes is manufactured by blow molding or a manufacturing method similar thereto. Blow molding is a method of forming a hollow member by extruding molten plastic into a tube shape and pressurizing the molten plastic along the inner mold. In blow molding, the wall thickness of the plastic when it becomes a tube may not be constant, and the film thickness of the liner, which is a molded product, may not be constant.
Therefore, the film thickness of the liner, which is a molded product, is measured using an ultrasonic film thickness meter to ensure the quality of the product.
For example, Patent Document 1 below is a method for non-destructively measuring the liner thickness of an outer lining tube having similar physical properties to the mother tube, and ultrasonic waves are incident on the inner surface of the outer lining tube from the inner surface side of the tube. The liner thickness is measured based on the reflected wave of the incident ultrasonic wave. The boundary surface reflected wave is detected without being affected by the front surface reflected wave and the back surface reflected wave.

Japanese Patent Application Laid-Open No. 08-159742

In the above-mentioned conventional technique, since the film thickness is manually measured one by one using an ultrasonic film thickness meter, there is a problem that it takes a lot of time and the production efficiency is poor. In particular, the liner of a large-capacity tank has a large surface area, and if the thickness of the entire area is manually measured and recorded, human cost will increase.

The present invention has been made in view of such circumstances, and an object of the present invention is to improve efficiency in measuring the thickness of an object over a wide range.

In order to achieve the above object, one embodiment of the present invention is a thickness measuring device for measuring the thickness of an object over a predetermined range, and the extending direction of the object is on one surface side of the object. A line-shaped light source that is arranged in parallel and irradiates light toward one surface of the object, and a line-shaped light source that is arranged side by side in parallel with the light source on the other surface side of the object and receives transmitted light transmitted through the object. A moving unit that moves the object while keeping the distance between the plurality of light receiving units, the object and the light source, and the distance between the object and the light receiving unit constant, and each of the light receiving units. It is characterized by including a thickness calculation unit for calculating the thickness of a portion of the object located between the light source and the light receiving unit based on the illuminance of the transmitted light received.
Further, one embodiment of the present invention is a thickness measuring method for measuring the thickness of an object over a predetermined range, and a line arranged on one surface side of the object parallel to the extending direction of the object. The object was transmitted by a light irradiation step of irradiating light from the shape of the light source toward the one surface and a plurality of light receiving portions arranged side by side in parallel with the light source on the other surface side of the object. A light receiving step of receiving transmitted light, a moving step of moving the object while keeping the distance between the object and the light source and the distance between the object and the light receiving portion constant, and the respective above. It is characterized by including a thickness calculation step of calculating the thickness of a portion of the object located between the light source and the light receiving portion based on the illuminance of the transmitted light received by the light receiving portion. ..

According to one embodiment of the present invention, it is possible to improve the efficiency when measuring the thickness of an object over a wide range.

It is a figure which shows the outline structure of the thickness measuring apparatus which concerns on embodiment. It is explanatory drawing which shows an example of the actual apparatus configuration of the thickness measuring apparatus. It is a flowchart which shows the procedure of thickness measurement by a thickness measuring apparatus. It is a figure which shows typically the measurement result of the thickness. It is explanatory drawing which shows typically an example of the correlation between the illuminance and the thickness of an object.

Hereinafter, preferred embodiments of the thickness measuring apparatus and the thickness measuring method according to the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a diagram showing a schematic configuration of a thickness measuring device according to an embodiment.
The thickness measuring device 10 measures the thickness of the object O over a predetermined range. In the present embodiment, measuring the thickness over a predetermined range means, for example, not measuring the thickness at several points sporadically, but at least a part of the range of the object O at a predetermined measurement interval. Refers to continuously measuring the thickness of multiple points.

The object O is, for example, a film-like member, and in the present embodiment, is a plastic liner of a fiber reinforced plastic container, specifically, an inner liner of an aircraft water tank having a cylindrical shape (curved surface shape), for example. And. It is assumed that the object O is a light-transmitting and opaque material (transparency is equal to or less than a predetermined value). That is, the object O has a light transmittance such that the irradiation light emitted from one surface in the thickness direction can be detected as transmitted light on the other surface, and the illuminance of the irradiation light and the illuminance of the transmitted light are different. It is assumed that a difference occurs depending on the thickness of the portion (light passing distance) (generally, irradiation light> transmitted light).

The thickness measuring device 10 includes a light source 12 and a light receiving unit 14 at positions facing each other with the object O in between. The light source 12 and the light receiving portion 14 are both formed in a line shape, and their extending directions are arranged parallel to the cylindrical axis of the object O, and are arranged at intervals in the radial direction of the cylinder.
The light source 12 is arranged in a line on one surface F1 side of the object O, and irradiates light toward one surface F1. In the light source 12, a plurality of point light sources (for example, LEDs) are arranged in a line, and each point light source emits light with a constant luminous flux to supply light having a constant illuminance to the irradiation side of the light source 12. As the light source 12, for example, a high-power LED work light formed in a line shape can be used.

The light receiving unit 14 is arranged side by side with the light source 12 on the other surface F2 side of the object O, and receives the transmitted light transmitted through the object O. In the light receiving unit 14, a plurality of light receiving elements are arranged in a line, and each light receiving element outputs an output according to the illuminance to detect the illuminance at the position of each light receiving unit 14. The illuminance refers to the amount of light incident per unit area, and is a physical quantity representing the degree of brightness of the surface illuminated by the light source. In the present embodiment, the intensity of light detected by the light receiving unit 14 is represented by illuminance, but other physical quantities representing the intensity of light may be used. In the present embodiment, a highly responsive and inexpensive silicon (Si) photodiode is used as the light receiving unit 14. In a silicon photodiode, the current generated by light reception is converted into a voltage and output.
It is assumed that the thickness measuring device 10 is installed in a dark room, and the light received by the light receiving unit 14 is only the light emitted from the light source 12.

In the present embodiment, the honeycomb structure 20 is arranged between the light source 12 and the object O or at least one of the light receiving unit 14 and the object O. In the example of FIG. 1, the honeycomb structure 20 (honeycomb core) is arranged both between the light source 12 and the object O and between the light receiving portion 14 and the object O.
By installing the honeycomb structure 20, the directions of the light passing through the portion can be aligned in one direction, and the thickness calculation accuracy in the calculation unit 18 described later can be improved. That is, the irradiation light L1 emitted by the light source 12 is diffused light and faces various directions. When the irradiation light L1 passes through the honeycomb structure 20, only the light along the extending direction of the opening of the honeycomb structure 20 reaches the opposite side (object O side) with respect to one surface F1 of the object O. The irradiation light L1'is vertically incident. The irradiation light L1'that has reached one surface F1 of the object O passes through the object O and is transmitted from the other surface F2 of the object O as transmitted light L2, but some light is scattered even in the object O. .. Therefore, the honeycomb structure 20 is also installed on the other surface F2 side, and the transmitted light L2'which has reduced the influence of the scattered light by passing through the honeycomb structure 20 is received by the light receiving unit 14.

The moving unit 16 moves the object O while keeping the distance between the object O and the light source 12 and the distance between the object O and the light receiving unit 14 constant. In the present embodiment, since the object O has a cylindrical shape, the moving portion 16 rotates the object O around the cylindrical axis. That is, the object O is moved in a direction orthogonal to the extending direction of the light source 12 and the light receiving unit 14 (the cylindrical tangential direction of the object O).
The moving unit 16 includes, for example, a support member that supports the object O, an actuator (motor) that moves the support member in a predetermined direction, and a detection unit (for example, an encoder) that detects the amount of movement of the actuator.
The thickness measuring device 10 can measure the thickness of the object O along the line by having the line-shaped light source 12 and the light receiving unit 14, and further, by moving the object O by the moving unit 16. , The thickness of the object O can be measured in a plane (over a predetermined range).

The thickness calculation unit 18 calculates the thickness of the portion of the object O located between the light source 12 and the light receiving unit 14 based on the illuminance of the transmitted light received by each light receiving unit 14. The thickness calculation unit 18 irradiates light from the light source 12 to the location of the object O whose thickness has been measured in advance with an ultrasonic film thickness meter or the like, and the light receiving unit 14 receives the illuminance to obtain the thickness and illuminance. The thickness is calculated based on the correlation with.

FIG. 5 is an explanatory diagram schematically showing an example of the correlation between the illuminance and the thickness of the object.
The object O is an opaque material, and when the illuminance of the incident light is constant, the illuminance of the transmitted light changes according to the thickness of the portion. More specifically, the thicker the portion, the more components are absorbed or scattered in the object O, and the darker the portion (the illuminance becomes lower).
In the example of FIG. 5, the illuminance is divided into eight stages, and the thickness corresponding to each stage is set. Although the illuminance is shown by shading in the drawing, the illuminance value (voltage value output from the photodiode) and the thickness are actually associated with each other.
For example, the thickness is 0.10 mm or less at the stage where the illuminance is the highest, the thickness is 0.11 mm or more and 0.12 mm or less at the stage where the illuminance is the second highest, and the thickness is 0.50 mm or more at the stage where the illuminance is the lowest. It is set. By using such a correspondence, the thickness of the portion of the object O facing the light receiving unit 14 can be calculated from the illuminance of the light received by the light receiving unit 14.

Here, in the object O, for example, the material or the compounding ratio of the material may be changed due to a change in the required specifications as a product. Further, it is preferable that the thickness measuring device 10 can measure the thickness of various types of objects (inner liner in the present embodiment) having different specifications.
Therefore, the thickness calculation unit 18 may maintain the correlation between the illuminance and the thickness for each of the material constituting the object O and the blending ratio of the material.
In addition, the correlation between the illuminance and the thickness may change depending on the type of the light source 12, the positional relationship between the light source 12 and the light receiving unit 14 and the object O (distance between them), and the like. .. Therefore, the thickness calculation unit 18 may maintain the correlation between the illuminance and the thickness for each of these parameters.

In addition, when the specifications such as the materials constituting the object O and the compounding ratio of the materials are changed, the correlation between the illuminance and the thickness is not obtained by actual measurement, but the known correlation is obtained by using machine learning or artificial intelligence (AI). The correlation in the specification may be estimated based on the relationship.
That is, it may further include an estimation unit 19 that estimates the correlation coefficient in an object configured by blending an arbitrary material at an arbitrary blending ratio based on a known correlation.
Further, the existing correlation does not apply even when the measurement conditions such as the type (model number, etc.) of the light source 12 and the light receiving unit 14 and the positional relationship between the light source 12 and the light receiving unit 14 are changed instead of the specifications of the object O. It may disappear. The estimation unit 19 may be applied to such a change so that a correlation under arbitrary measurement conditions can be obtained.
By providing the estimation unit 19, it is not necessary to obtain the correlation by actual measurement every time the specifications and measurement conditions of the object O are changed, and the production efficiency of the object O can be improved.

FIG. 2 is an explanatory diagram showing an example of an actual device configuration of the thickness measuring device.
The thickness measuring device 10 shown in FIG. 2 measures the thickness of the inner liner 300, which is the object O. The inner liner 300 has a substantially cylindrical shape (bale shape), and an opening 301 that serves as an entrance / exit for water is provided on the bottom surface of one side (upper side in FIG. 2).

An LED work light 302, which is a light source 12 on the line, is inserted into the inner liner 300 from the opening 301 along the axial direction of the inner liner 300. The LED work light 302 is supported by a movable light source support member (not shown). The light source support member is movable within a range in which the LED work light 302 can be inserted from the outside of the inner liner 300 into the inside of the inner liner 300.
The light irradiation direction of the LED work light 302 (the direction in which the light intensity is highest) is arranged so as to be the light receiving portion 14 direction.

A honeycomb core 314, which is a honeycomb structure 20, is arranged on the front surface (light irradiation direction) of the LED work light 302, and among the irradiation light from the LED work light 302, the light directed in the radial direction of the inner liner 300. Only reaches the inner liner 300 side.

Outside the inner liner 300, a photodiode unit 304 in which a plurality of silicon photodiodes are linearly arranged is arranged. The photodiode unit 304 is provided at a position where the LED work light 302 and the inner liner 300 are opposed to each other, and the light detection direction is directed to the LED work light 302 side. The photodiode unit 304 is supported by a fixed light receiving portion support member (not shown).

A honeycomb core 314, which is a honeycomb structure 20, is arranged on the front surface (light detection direction) of the photodiode unit 304, and of the transmitted light from the inner liner 300, only the light directed in the radial direction of the inner liner 300. Reaches the photodiode unit 304 side.
The voltage output from each diode of the photodiode unit 304 is converted into a digital signal via the A / D converter 312 and input to the computer 308.

In FIG. 2, the LED work light 302 is arranged inside the inner liner 300 and the photodiode unit 304 is arranged outside the object O. However, the LED work light 302 is arranged outside the inner liner 300 and the photodiode unit. The 304s may be arranged inside the object O, respectively.

The inner liner 300 is mounted on a circular turntable 310, and the turntable 310 can be rotated by a motor 306 which is a moving portion 16.
When the motor 306 rotates, the turntable 310 rotates, and the inner liner 300 also rotates accordingly. On the other hand, the LED work light 302 and the photodiode unit 304 are fixed, and the inner liner 300 passes between the LED work light 302 and the photodiode unit 304.
The on / off of the motor 306 is controlled by the computer 308 which is the thickness calculation unit 18 and the estimation unit 19, and the rotation state (rotation angle) of the motor 306 is detected by the built-in encoder and output to the computer 308. ..

For example, when the inner liner 300 is placed on the turntable 310, the thickness can be increased by aligning the split mark of the mold transferred at the time of blow molding of the inner liner 300 with the reference position mark attached to the turntable 310. The measurement result can be easily collated with the position of the inner liner 300.

Further, in FIG. 2, each component of the thickness measuring device 10 is arranged so that the inner liner 300 is placed so as to be placed in the vertical direction, but the inner liner 300 can be held sideways. When it has hardness, each component of the thickness measuring device 10 may be arranged so that the inner liner 300 is placed so that the axial direction is directed to the horizontal direction.

The computer 308, which is the calculation unit 18, associates the voltage value (illuminance data) output from the photodiode unit 304 with the rotation angle output from the encoder to correlate the position and voltage value of the inner liner 300 in the circumferential direction. And associate with. Then, the voltage value is converted into the thickness of the inner liner 300 by using the correlation as shown in FIG. 5, and the thickness at each point of the inner liner 300 is calculated. The voltage value may be converted into the thickness and then associated with the rotation angle.

FIG. 4 is a diagram schematically showing the measurement result of the thickness.
In FIG. 4, the vertical axis represents the thickness of the inner liner 300, and the horizontal axis represents the rotation angle from the reference position. Each system D1 to D4 corresponds to each photodiode of the photodiode unit 304, and indicates a position along the axial direction of the inner liner 300. Although only four systems are shown in FIG. 4, the photodiode unit 304 is actually composed of several tens of photodiodes, and the same number of systems are output as measurement results. ..
The target thickness (or threshold value) shown on the vertical axis is the minimum value of the thickness required for the inner liner 300. In FIG. 4, the measured value of each system exceeds the target thickness of the inner liner 300 over the entire circumference. That is, the inner liner 300 to be measured satisfies the thickness requirement. If there is a portion that does not meet the target thickness of the inner liner 300, the coordinates of that portion can be easily specified.
Further, the maximum value of the target thickness may be further set, and it may be determined whether or not the thickness of the inner liner 300 is within the range from the minimum value to the maximum value.

FIG. 3 is a flowchart showing a procedure for measuring the thickness by the thickness measuring device.
First, the person in charge of measurement installs the inner liner 300 to be measured on the turntable 310 (step S300). Further, the person in charge of measurement moves the light source support member, arranges the LED work light 302 (light source) inside the inner liner 300, and causes the LED work light 302 (light source) to emit light (step S302: light irradiation step).
Next, the person in charge of measurement sets the section in which the thickness measuring device 10 is installed in a dark room state, and starts detecting the illuminance by the photodiode unit 304 (light receiving unit) (step S304: light receiving step). The detected illuminance is output to the computer 308. When the person in charge of measurement starts the rotation of the turntable 310, the encoder detects the rotation angle of the turntable 310 and outputs it to the computer 308 (step S306: moving step).
The computer 308 associates the illuminance data output from the photodiode unit 304 with the rotation angle data output from the encoder (step S308). Further, the computer 308 converts the illuminance data into a thickness based on the correlation as shown in FIG. 5 (step S310), and outputs a thickness distribution indicating the thickness at each point of the inner liner 300 (step S310). S312: Thickness calculation step), the process of this flowchart is completed.

As described above, the thickness measuring device 10 according to the embodiment irradiates the object O to be measured with light from the light source 12, and determines the thickness of the object O based on the illuminance of the transmitted light transmitted through the object O. calculate. The light source 12 and the light receiving unit 14 are formed in a line shape, and move the object O with respect to the light source 12 and the light receiving unit 14. As a result, the thickness can be measured in a plane, and the measurement work can be performed in a short time as compared with the case where the thickness is manually measured one by one. In addition, the measured value of the thickness and the position on the object O can be accurately and automatically recorded, and the efficiency and accuracy of the measurement work can be improved.
Further, the thickness measuring device 10 is based on the correlation between the thickness and the illuminance obtained by irradiating the portion of the object O whose thickness has been actually measured in advance with light from the light source 12 and receiving the illuminance by the light receiving unit 14. Since the thickness is calculated, the thickness can be measured efficiently and accurately.
Further, since the thickness measuring device 10 maintains the correlation between the thickness and the illuminance for each of the material constituting the object O and the compounding ratio of the material, the thickness measuring device 10 appropriately matches the specifications of the object O (material and its compounding ratio). Measurements can be made.
Further, if the thickness measuring device 10 estimates the correlation coefficient in an object configured by blending an arbitrary material at an arbitrary blending ratio based on a known correlation, the specification of the object O can be changed. At times, the correlation between thickness and illuminance can be obtained without actually measuring, and the efficiency of measurement work can be improved.
Further, in the thickness measuring device 10, if the honeycomb structure 20 is arranged between the light source 12 and the object O or between the light receiving portion 14 and the object O, the influence of the scattered light is reduced. However, the thickness can be measured with higher accuracy.

In the present embodiment, the object O is a plastic liner 300 of a fiber-reinforced plastic container, but the present invention is not limited to this, and the irradiation light emitted from one surface in the thickness direction is applied to the other surface. If the object has light transmittance that can be detected as transmitted light, and there is a difference between the illuminance of the irradiation light and the illuminance of the transmitted light according to the thickness of the part (light passing distance), the thickness of the object. The thickness can be measured by the measuring device 10.

10 Thickness measuring device 12 Light source 14 Light receiving part 16 Moving part 18 Calculation part 19 Estimating part 20 Honeycomb structure 300 Inner liner 302 LED work light 304 Photodiode unit 306 Motor 308 Computer 310 Turntable 312 Converter 314 Honeycomb core O Object

Claims

A thickness measuring device that measures the thickness of an object over a predetermined range.
A line-shaped light source arranged on one surface side of the object parallel to the extending direction of the object and irradiating light toward the one surface.
A plurality of light receiving portions arranged side by side in parallel with the light source on the other surface side of the object and receiving the transmitted light transmitted through the object.
A moving unit that moves the object while keeping the distance between the object and the light source and the distance between the object and the light receiving unit constant.
A thickness calculation unit that calculates the thickness of a portion of the object located between the light source and the light receiving unit based on the illuminance of the transmitted light received by each light receiving unit.
A thickness measuring device comprising.
The thickness calculation unit is based on the correlation between the thickness and the illuminance obtained by irradiating the portion of the object whose thickness has been actually measured in advance with light from the light source and receiving the illuminance by the light receiving unit. To calculate the thickness,
The thickness measuring apparatus according to claim 1.
The thickness calculation unit maintains the correlation for each of the materials constituting the object and the blending ratio of the materials.
2. The thickness measuring device according to claim 2.
Further provided is an estimation unit that estimates the correlation coefficient in an object constructed by blending an arbitrary material at an arbitrary blending ratio based on the known correlation.
3. The thickness measuring device according to claim 3.
A honeycomb structure is arranged between the light source and the object or at least one of the light receiving portion and the object.
The thickness measuring device according to any one of claims 1 to 4, wherein the thickness measuring device is characterized.
The object has a cylindrical shape
The moving portion rotates the object around the cylindrical axis.
The thickness measuring device according to any one of claims 1 to 5, wherein the thickness measuring device is characterized.
The object is a plastic liner of a fiber reinforced plastic container,
The thickness measuring apparatus according to claim 6.
A thickness measuring method for measuring the thickness of an object over a predetermined range.
A light irradiation step of irradiating light from a line-shaped light source arranged on one surface side of the object parallel to the extending direction of the object toward the one surface.
A light receiving step of receiving the transmitted light transmitted through the object by a plurality of light receiving portions arranged side by side in parallel with the light source on the other surface side of the object.
A moving step of moving the object while keeping the distance between the object and the light source and the distance between the object and the light receiving portion constant.
A thickness calculation step of calculating the thickness of a portion of the object located between the light source and the light receiving portion based on the illuminance of the transmitted light received by each of the light receiving portions.
A thickness measuring method characterized by containing.
The object has a cylindrical shape
The movement of the object by the moving step is performed by rotating the object around the cylindrical axis.
In the moving step, the rotation angle of the object is detected.
In the thickness calculation step, a thickness distribution in which the detected rotation angle of the object is associated with the calculated thickness of the portion of the object is output.
The thickness measuring method according to claim 8, wherein the thickness is measured.