JP2000205830A - Method and device for measuring thickness of coating - Google Patents

Abstract

PROBLEM TO BE SOLVED: To measure the thickness of paint in a state before drying and hardening with high accuracy without contact independently of the type of an object to be measured and the paint, by measuring the distance from a reference surface to a body to be painted before painting and the distance from the reference surface to the paint surface after painting through the use of laser displacement meters, and computing the difference between both measured distances. SOLUTION: A reference surface is placed on the same circumferential surface at a predetermined distance from the center of a packing roll 2, the locations of a steel plate S in coil before painting and a steel plate S' in coil after painting on the packing roll 2 from the reference surface are each measured by laser displacement meters 11 and 12. The surface location of the steel plate S' after painting captured by the laser displacement meter 12 is changed by the thickness of the paint film with respect to the location of the steel plate S before painting captured by the laser displacement meter 11. Therefore, by measuring the distance L1 from the reference surface to a body to be painted before painting and the distance L2 from the reference surface to the paint surface after painting, inputted them to a paint film thickness computing means 21 to compute L2-L1, and displaying the result of the computation on a paint film thickness displaying means 22, the thickness of the paint film is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the thickness of a coating film (coating film thickness,
In the following, it is also referred to simply as "coating film thickness"). In particular, the coating film thickness on a continuously flowing metal plate such as a steel strip is measured in a non-contact manner using a laser before drying and curing. It relates to means for measuring.

[0002]

2. Description of the Related Art In the production of colored steel sheets, a coating process is performed in which a coating is applied to the surface of the steel sheet and then dried and hardened. In this process, the coating thickness on the steel sheet is maintained as uniform as possible. Is important in terms of product quality, especially in avoiding different colors. In particular, when a coating film is formed on a continuously supplied metal steel strip such as a steel strip, it is extremely important to keep its thickness uniform throughout its length and width. Therefore, it is necessary to measure the thickness of the coating film immediately after coating, and to feed back to the operating conditions of a coating apparatus such as a roll coater to quickly correct the operating conditions.

In response to such demands, a number of means for continuously measuring the thickness of a coating film on a metal plate in a non-contact state have been proposed. -248408 proposes to measure the distance to the coating surface using a laser displacement meter, measure the distance to the metal surface using a magnetic displacement meter, and calculate the difference between the two as the coating thickness. Means have been proposed. In addition, JP-A-6-160030 discloses that an object to be measured is placed in a constant magnetic field,
Faraday rotation angle (deflection angle) for reflected laser light
A method for determining the thickness of the coating film by measuring the thickness of the coating has also been proposed.

[0004]

However, the above-mentioned Japanese Patent Laid-Open No.
The method proposed in 248408 is applicable when the metal plates are all magnetic materials, but when a non-magnetic material exists on the surface such as a plated steel plate, it is necessary to correct the thickness. In fact, when the thickness of the non-magnetic material portion such as the plating thickness fluctuates, it is practically difficult to apply. Furthermore, it cannot be applied to a non-magnetic metal plate such as an aluminum plate. On the other hand, the method proposed in JP-A-6-160030 discloses a relational expression between the coating film thickness (L) and the displacement angle (θ), θ = V
The Verde constant (V) in HL (H is an applied magnetic field) must be changed each time the type of paint changes, which imposes a heavy load on measurement.

SUMMARY OF THE INVENTION The present invention has been made to solve the problems of the prior art, and it is an object of the present invention to change the characteristic value of a laser beam regardless of the type of an object to be measured or the type of a paint. Further, the present invention provides a simple means for measuring the thickness of a coating film applied on an object to be measured in a state before drying and curing in a non-contact manner and with extremely high accuracy.

[0006]

The present invention skillfully utilizes the property that the distance from a reference plane to an object to be measured can always be measured accurately regardless of the properties of the article by using a laser displacement meter. There are two methods of measuring the coating film thickness: measuring the distance from the reference surface to the object to be coated in a state before coating using a laser displacement meter, and measuring the position of the surface of the object to be coated with another reference surface in the state after coating. And a coating surface position step of measuring the distance from the coating surface by a laser displacement meter, and a difference between the distance measured by the object surface position measuring step and the distance measured by the coating surface position measuring step. And a film thickness calculating step of calculating the film thickness based on the above.

Further, the present invention provides a method for measuring a coating film thickness.
In the state before coating, the distance from the two laser displacement gauges provided opposite to each other with the object to be coated being measured to the object to be coated is calculated and the sum thereof is calculated. From the distance between the two laser displacement meters, The thickness of the object to be coated is calculated by calculating the value obtained by subtracting the sum as the thickness of the object to be coated. In the state after the coating, the coating film is formed from two laser displacement meters provided opposite each other with the coated object interposed therebetween. Measuring the distance to the surface and calculating the sum thereof, and calculating a value obtained by subtracting the sum from the distance between the two laser displacement gauges as the thickness of the coated body; and As having a coating film thickness calculation step of calculating the difference between the value measured by the body thickness measurement step and the value measured by the coating body thickness measurement step as a coating film thickness, the coated articles during operation etc. Always stable even when vibrating It is obtained by allowing measurement of paint thickness.

The present invention further provides an apparatus for measuring a coating film thickness,
A laser displacement meter on the front side that measures the distance from the reference surface to the object to be coated, which is installed on the front side of the coating device, and measures the distance from the other reference surface to the coating surface, which is installed on the back side of the coating device. The rear laser displacement meter to be input, the distance from the reference surface by the front laser displacement meter to the object to be coated and the distance from the other reference surface by the rear laser displacement meter to the coating surface, and And a coating film thickness calculating means for calculating the coating film thickness based on the difference.

The present invention further provides an apparatus for measuring a coating film thickness,
Two front-side laser displacement meters that are provided on the front side of the coating apparatus and face each other with a body to be coated interposed therebetween and measure a distance to the body to be coated. An object thickness calculating means for calculating the sum of the distances and calculating the difference between the distance between the two laser displacement gauges and the sum as the thickness of the object to be coated; And two rear-side laser displacement meters for measuring the distance to the coating surface, and calculating the sum of the distances from the two rear-side laser displacement meters to the coating surface and the two rear surfaces. Coating body thickness calculating means for calculating the difference between the distance between the side laser displacement gauges and the sum as the thickness of the coating body, and the thickness of the body to be coated and the thickness of the coating body obtained by the means for calculating the thickness of the body to be coated The difference between the thickness of the paint body obtained by the calculation means is calculated and the And to have a paint film thickness calculation means for outputting Te, the one in which the object to be measured is a device which can advantageously be applied also in the case of vibration.

Further, in the present invention, there is provided the apparatus for measuring a coating film thickness, wherein the measuring apparatus for the coating film thickness comprises a means for detecting a coating material transport speed, a speed obtained from the coating material transport speed detecting means, and a front side laser displacement. Means for calculating a delay time for the coating body to pass between the front-side laser displacement meter and the rear-side laser displacement meter based on a distance between the meter and the rear-side laser displacement meter; and a front-side laser in accordance with the delay time. Means for outputting a measurement result of the displacement meter, and the front side laser displacement meter and the rear side laser displacement meter are provided at the same position in the width direction on the coating body conveying line, thereby the object to be measured. This enables measurement of the film thickness at the same position.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a colored paint is applied to a steel sheet,
An embodiment of the present invention will be specifically described by taking an example of measuring the thickness of a coating film when manufacturing a so-called color steel sheet.

FIG. 1 is a front view showing an embodiment of a coating film thickness measuring apparatus suitable for carrying out the present invention. Steel plate S
It is wound around the backing roll 2 from the holdback roll 1 and advances in the direction of the arrow with a constant tension applied. An applicator roll 6 is installed close to the backing roll 2, and a pickup roll 5
The coating liquid 4 filled in the coating pan 3 is applied to the steel strip S to form a coated steel strip S ′. This roll coater device is provided with a front-side laser displacement meter 11 and a rear-side laser displacement meter 12 so that the coating film thickness can be measured on a backing roll.

The laser displacement meters 11 and 12 are composed of a light emitting element and a light receiving element. After the light emitted from the light emitting element passes through the light projecting side lens, the object to be measured (in this case, steel The light is diffusely reflected on the surface of the band S or the coated steel band S '), and a part of the reflected light is condensed by the custom lens on the light receiving side to form a spot on the CCD. When the object is displaced, the angle at which the diffuse reflected light is condensed changes, and the spot on the CCD moves accordingly, so that the displacement of the object can be measured by detecting its position. Has become.

In the embodiment of the present invention shown in FIG. 1, the reference surface is placed on the same circumferential surface at a fixed distance from the center of the backing roll 2, and the steel strip S and the paint before the application of the paint on the backing roll 2. Are disposed so that the positions of the steel strip S ′ (hereinafter referred to as “painted steel strip”) applied from the reference surface can be measured by the front-side laser displacement meter 11 and the rear-side laser displacement meter 12, respectively. Therefore, the surface position of the coated steel strip S ′ captured by the rear laser displacement meter changes by the thickness of the coating film 7 with respect to the position of the steel strip S captured by the front laser displacement meter 11. Therefore, the distance from the reference surface to the object to be coated is measured with a laser displacement meter in the state before painting, and then the same measurement is performed in the state after painting, and the difference between the former measurement result and the latter measurement result is determined. If found, the thickness of the coating film can be calculated.

Specifically, as shown in FIG. 3, the measurement results L ₁ and L ₂ by the laser displacement meters 11 and 12 are input to the coating film thickness calculating means 21 as shown in FIG. ₂ −
L ₁ can be performed by calculating the. The calculation result may be displayed on the coating film thickness display means 22, for example.

In the above example, the measurement reference planes of the two laser displacement meters are placed on the same circumferential surface at a fixed distance from the center of the backing roll 2, but this is not always necessary. When the reference surface of the front-side laser displacement meter 11 and the reference surface of the rear-side laser displacement meter are different, it is natural that the difference should be corrected in the measurement result.

According to the configuration shown in FIGS. 1 and 3,
The thickness of the coating on the steel strip can be measured.
Inaccurate measurement results when vibrating during transportation
Could be In such a case, before and after paint application
Change in thickness can be measured as coating thickness
No. First, the thickness of the steel sheet S to be coated
-Measured by the displacement meter 13. That is, as shown in FIG.
As shown, the two laser displacement meters 13a and 13b are
As shown in FIG.
Two laser displacement gauges facing each other to maintain
Then, the steel sheet S is passed between the gaps.
From the two laser displacement meters 13a and 13b,
Distance L to the surface_ThreeAnd L_FourAre measured respectively. Leh
The distance between the displacement meters 13a and 13b is L_FiveAlready
Because it is knowledge, L_ThreeAnd L _FourSubtract the sum of
For example, the thickness of the steel sheet S can be calculated.

[0018] Next, the coated steel sheet S 'coated with paint 3 on the steel sheet S, the laser displacement meter 14 in the upper and lower pairs of laser displacement meter 14a and 14b, performs the same measurement as described above, L ₈ The thickness of the coated steel sheet is measured by calculating − (L ₆ + L ₇ ).

Finally, the difference between the thickness of the steel strip S before coating and the thickness of the coated steel strip S 'obtained by the above measurement is calculated as the coating film thickness.

Specifically, as shown in FIG. 4, a pair of laser displacement gauges 13a and 13b are provided on the front side of the coating apparatus with the steel strip S interposed therebetween, as shown in FIG. The value measured by the above-mentioned pair of laser displacement meters 13
a, by entering with the distance between 13b L ₅ - (L ₃ +
L ₄ ) is calculated by calculating the thickness of the steel strip by performing the calculation of L ₄ ), laser displacement meters 14 a and 14 b performing the same operation,
L ₈ and input pair of laser displacement meter 14a, with the distance between 14b - and (L ₆ + L ₇₎ coating layer body thickness calculating unit 24 for calculating the performed to calculate the thickness of coating steel strip, these The difference may be constituted by the coating film thickness calculating means 25 for calculating the coating film thickness and the coating film thickness displaying means 26 for displaying the result. The means for determining the coating thickness based on the difference between the thicknesses of the steel strip S and the coated steel strip S ′ is more accurate since the vibration of the steel strip S does not affect the measurement result of the thickness itself. A measurement can be made.

In the above-mentioned film thickness measurement, laser displacement meters are arranged on the front side and the rear side of the coating apparatus, and the film thickness is represented by the difference between the two measurement results. Therefore, if the distance between the front laser displacement meter and the rear laser displacement meter is long, or if the plate thickness fluctuates drastically, the rear laser displacement meter should be accurately positioned at the position corresponding to the position measured by the front laser displacement meter. It is important to measure the laser displacement meter. In the width direction of the steel strip, it is important to match the measurement positions on the front and rear surfaces.

In order to cope with such a case, in the present invention, the conveying speed of the steel strip S is measured by, for example, PLG,
Also, given the distance between the front side laser displacement meter (11 or 13) and the rear side laser displacement meter (12 or 14), the painted body passes between the front side laser displacement meter and the rear side laser displacement meter. Is calculated, the measurement result of the front-side laser displacement meter is held for that time, and the result is output when the steel strip passes through the rear-side laser displacement meter.

To match the measurement positions in the width direction, for example, as shown in FIG.
3a and 13b are fixedly held by a displacement meter
, And the sliding rod 3 fixed to the support 34
It is preferable that the position of the laser displacement meter 14 in the width direction of the steel strip can be adjusted by sliding on the top 3. For example, as shown in FIG. 5, the measurement can always be performed on the center line (C) of the steel strip S. In this case, it is optional to measure at many points in the width direction or to measure at points off the center line.

Although the embodiment of the present invention has been described by taking the case of manufacturing a color steel strip as an example, the present invention is applicable to a metal plate other than a steel strip, such as a copper or aluminum plate, or a plastic sheet or a cut sheet. Of course, it can also be applied.

[0025]

According to the present invention, the coating thickness is measured based on the surface displacement before and after coating using the laser displacement meter as described above, so that the coating thickness can be measured very accurately. As a result, the occurrence of different colors of painted steel plates has been drastically reduced.

[Brief description of the drawings]

FIG. 1 is a front view showing one embodiment of a coating film thickness measuring device suitable for carrying out the present invention.

FIG. 2 is a front view showing another embodiment of a coating film thickness measuring apparatus suitable for carrying out the present invention.

FIG. 3 is an explanatory view showing a coating film thickness measuring mechanism according to the present invention.

FIG. 4 is an explanatory view showing a coating film thickness measuring mechanism according to another embodiment of the present invention.

FIG. 5 is a plan view showing an example of an arrangement of a laser displacement meter when the present invention is implemented.

FIG. 6 is a cross-sectional view showing a width direction moving mechanism of the laser displacement meter when implementing the present invention.

[Explanation of symbols]

 1: hold back roll 2: backing roll 3: paint pan 4: paint liquid 5: pickup roll 6: applicator roll 7: coating film 11: front side laser displacement meter 12: rear side laser displacement meter 13: front side laser displacement meter 14: Backside laser displacement meter 21: Film thickness calculating means 22: Film thickness displaying means 23: Painted body thickness calculating means 24: Painted body thickness calculating means 25: Film thickness calculating means 26: Film coating Thickness display means 31: Displacement meter support 32: Sliding body 33: Sliding rod 34: Support S: Steel plate S ': Painted steel plate

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2F065 AA30 BB13 BB17 BB24 CC02 CC06 DD03 FF43 GG04 HH04 HH13 JJ01 JJ05 JJ15 QQ25

Claims (5)

[Claims] 1. A step of measuring a distance from a reference surface to an object to be coated in a state before coating by a laser displacement meter, and a step of measuring a surface position of the object from another reference surface to a film surface in a state after coating. The coating film position position step of measuring the distance with a laser displacement meter, and the coating film thickness based on the difference between the distance measured by the coated object surface position measuring step and the distance measured by the coating film surface position measuring step. And calculating a coating film thickness. 2. In a state before coating, a distance between two laser displacement meters provided opposite to each other with the object to be coated therebetween is measured, and a sum thereof is calculated. The thickness of the object to be coated, in which a value obtained by subtracting the sum from the distance between the gauges is calculated as the thickness of the object to be coated; and two lasers provided opposite to each other with the object being coated in a state after coating. Measuring the distance from the displacement meter to the coating surface and calculating the sum thereof; and calculating the value obtained by subtracting the sum from the distance between the two laser displacement meters as the thickness of the coated body. And, having a coating film thickness calculation step of calculating the difference between the value measured in the coating object thickness measurement step and the value measured in the coating body thickness measurement step as a coating film thickness. The method of measuring the coating film thickness. 3. A front-side laser displacement meter provided on the front side of the coating apparatus and measuring a distance from a reference plane to an object to be coated; Backside laser displacement meter to measure the distance to, the distance from the reference surface by the front side laser displacement meter to the object to be coated and the distance from the other reference surface by the backside laser displacement meter to the coating surface and And a coating film thickness calculating means for calculating the coating film thickness based on the difference. 4. A two-sided laser displacement meter, which is provided on the front side of the coating apparatus and faces the object to be coated with the object to be coated interposed therebetween, and measures a distance to the object to be coated; An object thickness calculating means for calculating the sum of the distances to the object to be coated and calculating the difference between the distance between the two laser displacement meters and the sum as the thickness of the object to be coated; Are provided facing each other with the painted body in between,
Two rear-side laser displacement meters for measuring the distance to the coating surface, and calculating the sum of the distance from the two rear-side laser displacement meters to the coating surface and the distance between the two rear-side laser displacement meters And a coated body thickness calculating means for calculating the difference between the sum and the coated body thickness, and a coated body thickness obtained by the coated body thickness calculating means and a coated body obtained by the coated body thickness calculating means. An apparatus for measuring a coating film thickness, comprising a coating film thickness calculating means for calculating a difference from the thickness and outputting as a coating film thickness. 5. A coating film thickness measuring device, comprising: a coating body transport speed detecting means; a speed obtained from the coating body transport speed detecting means; and a distance between the front side laser displacement meter and the rear side laser displacement meter. Means for calculating a delay time when the coating body passes between the front side laser displacement meter and the rear side laser displacement meter, and means for outputting a measurement result of the front side laser displacement meter in accordance with the delay time The coating film thickness measuring device according to claim 3 or 4, wherein the front side laser displacement meter and the rear side laser displacement meter are provided at the same position in the width direction on the coating body conveying line.