JPH1172436A - Method and apparatus for measuring oil-application amount on metallic material surface - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an apparatus for measuring an application amount of oil on a metallic material surface which can simply and easily measure a coat amount of oil with high measurement accuracy at an area of a low coat amount both off-line and online. SOLUTION: The apparatus is provided with an excitation light source 6 which projects an excitation light of rectangular beams of a specific wavelength to a metallic material surface where an oil is applied, an optical system 12 which condenses a fluorescent light generated by the excitation light from the metallic material surface and forms a rectangular fluorescent image on a rectangular slit 13, a spectroscope 14 splitting the fluorescent light introduced via the slit 13, and a photodetecting element 15 which detects the fluorescent light split by the spectroscope 14 and measures an intensity of the fluorescent light. The rectangular slit 13 is arranged so that the direction of a long side is orthogonal to the direction of a long side of the rectangular fluorescent image.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for measuring the amount of oil applied to the surface of a metal material, and more particularly to a method for easily and easily measuring the amount of a small amount of oil applied to the surface of a metal material such as a steel plate or an aluminum plate. The present invention relates to a method and an apparatus for measuring the amount of oil applied to a metal material surface, which can be measured with high accuracy.

[0002]

2. Description of the Related Art The amount of oil applied to a metal plate surface for rust prevention and lubrication during press molding is an important management item that determines the characteristics of rust prevention and press molding. Normally, a sample is cut out from a metal plate that is continuously produced, the weight of the sample at the time of oil adhesion and the weight of the sample after oil degreasing are measured, and the difference between the two is calculated to calculate the amount of oil applied per unit area. However, recently, since stricter quality control is required, a continuous online oiling amount measuring device capable of measuring even while a metal plate to be measured is running (Japanese Patent Application Laid-Open No. 7-24397)
No. 0) and, conversely, a compact and lightweight off-line oil coating amount measurement device (New methods for qualit
y assurance in metal forming, 18th Bi-ennial Congre
ss IDDRG 1994) has been developed and put into practical use. The former uses a laser-induced fluorescence method, and the latter uses an infrared absorption method.

[0003]

However, in the former case using the laser-induced fluorescence method, for example, cold-rolled steel sheets and various plating materials that are being continuously produced in a cold rolling process or a surface treatment process in the steel industry. Assuming that the amount of oil applied on the surface can be measured online, the measurement range of the amount of oil applied is also 100 to 20.
Since a relatively large amount of 00 mg / m ² is targeted, an industrially stable and high-output laser is used. As a result, there is a problem that the apparatus becomes large and the price is high, so that it is difficult to use it off-line. .

On the other hand, in the case of using the latter infrared absorption method, the degree of infrared absorption of the applied oil can be reduced even if the condition of compactness and low price required for an off-line device is satisfied, for example, by the surface characteristics of the underlying metal material. Surface roughness, rolling directionality,
The problem of poor measurement accuracy in the low oil application range is that it is susceptible to the effects of reflectivity, etc. and the state of oil adhesion, for example, whether the oil adheres in granular or film form. is there.

Accordingly, the present invention has been made in view of such problems of the prior art, and intensively receives the fluorescence induced by the excitation light applied to the oil-coated metal surface to be measured. By measuring the fluorescence intensity by introducing it to the optical system, the fluorescence intensity measurement error due to variations in the roughness of the surface to be measured and the positional relationship with the measurement device has been reduced. However, an object of the present invention is to provide a method and an apparatus for measuring the amount of oil applied to the surface of a metal material, which can easily and easily measure the amount of oil applied even online.

[0006]

According to a first aspect of the present invention, there is provided a method for measuring the amount of oil applied to a surface of a metal material, the method comprising: Irradiating the excitation light of the wavelength, condensing the fluorescence generated by the irradiation, forming a rectangular fluorescent image at the rectangular slit position, and making the long side direction of the fluorescent image orthogonal to the long side direction of the slit. The center of each rectangle is matched, and the intensity of the fluorescence that has passed through the slit is measured to determine the amount of oil applied.

[0007] Further, according to a second aspect of the present invention, there is provided an apparatus for measuring the amount of oil applied to a surface of a metal material, comprising: a means for irradiating the surface of the metal material coated with oil with excitation light having a rectangular beam shape and a specific wavelength;
An optical system that collects fluorescence from the metal material surface generated by the excitation light and forms a rectangular fluorescence image at a rectangular slit position, a spectroscope that disperses the fluorescence guided through the slit, and A means for detecting the fluorescence separated by the spectroscope to measure the fluorescence intensity, and a means for calculating the amount of oil applied based on the fluorescence intensity, wherein the rectangular slit has its long side directed to the rectangular fluorescence. It is characterized by being arranged so as to be orthogonal to the long side direction of the image.

According to a third aspect of the present invention, there is provided the apparatus for measuring the amount of oil applied to the surface of a metal material according to the second aspect.
A holding device for holding the metal material to be measured at a predetermined measurement position is provided.

It is known that when the surface of oil applied on a metal plate such as a steel plate is irradiated with light having an excitation wavelength suitable for the oil, the oil emits fluorescence. It has been found that there is a proportional relationship between. For example, when examining the fluorescent properties of rust-preventive oil, which is often used in the temper rolling step and the refining step after cold rolling, the fluorescent light is efficiently emitted when excited around a wavelength of 330 to 350 nm, which is an ultraviolet wavelength region. Fluorescence peaks at wavelengths of
The result was about 0 nm, and fluorescence can be observed with the naked eye. The inventors of the present application have repeatedly conducted experiments using this principle to realize a compact measurement of the amount of applied oil which can be particularly suitably applied to off-line measurement.
It has been found that a nitrogen (N ₂ ) pulse laser of m can be suitably used. Conventionally, N ₂ pulse lasers have been used for physics and chemistry experiments, and there were many relatively large devices. Recently, a small laser that can continuously emit 20 million pulses without circulating N ₂ gas is used. Oscillators are commercially available at low cost. Therefore, when using such a laser oscillator, for example, an N ₂ laser beam having a repetition frequency of 20 Hz and an energy of 120 μJ per pulse is condensed and applied to oil on a steel plate, and the fluorescence intensity is measured in a pulse-synchronized manner. It was found that fluorescence detection with a good / N ratio was possible, and that it was applicable to measurement of the amount of applied oil.

[0010] For example, when the off-line oil amount measurement is configured using an N ₂ laser, the oil amount is 100%.
In order to measure with high accuracy in the low oiling amount range of less than mg / m ^2, it is effective to focus the laser beam using a lens to increase the fluorescence efficiency and irradiate the metal material surface. found.

On the other hand, in off-line measurement, a sample is cut out and mounted on an oiling amount measuring device for measurement, or the oiling amount measuring device is pressed against a sheet-like or coil-like metal material surface, or It is preferable that both the case where the measurement is carried out on the surface of the metal material and the case where the measurement is carried out is assumed, and the case can be used in each case. However, in these cases, the light guide state of the received fluorescent beam to the light receiving optical system is slightly different due to the difference in positional accuracy such as the minute uneven shape of the metal material surface and the way of mounting the sample on the device and pressing it. This may result in a fluorescence intensity error and a final oil coating amount measurement error. Accordingly, the present inventors have conducted research to address the drawbacks of off-line measurement and to increase the reliability of the measured values. As a result, even if the position of the measurement surface fluctuates or tilts slightly, the fluorescent light received In order to reduce the measurement error by stably guiding to the light receiving optical system, each of the irradiation light beam shape and the light receiving slit shape is rectangular, and the centers of the rectangles are aligned so that the long side of each rectangle is The inventors have found that it is effective to determine the three-dimensional arrangement of the excitation light and the slit so as to be orthogonal to each other, and have accomplished the present invention.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram illustrating the entire configuration of the apparatus for measuring the amount of oil applied to the surface of a metal material according to the present invention.
In the figure, reference numeral 1 denotes a detection head for measuring the amount of applied oil, which is small and light enough to be portable. This detection head 1
Is provided with a detachable sample holder 2 as a holding device for holding an oil-coated metal sample to be measured (hereinafter referred to as a work) W at a predetermined measurement position. The work W in this case is a work W cut and collected in the process line, but by removing the sample holder 2, the detection head 1 is brought into direct contact with the sheet-shaped or coil-shaped metal material to perform measurement. You can also. Reference numeral 3 denotes a signal control processing device connected to the detection head 1 and has a function of controlling a laser transmission timing described later and a detection timing of a detection element for measuring a fluorescence intensity. Reference numeral 4 denotes an arithmetic processing unit as oiling amount calculation means, which calculates the oiling amount from the measured value of the signal processed by the signal control processing unit 3, measures a calibration plate, and inputs a calibration curve. Control the measurement procedure.

The detection head 1 is, as shown in FIG.
A specific wavelength of a rectangular beam on the surface of the work W
An excitation light source 6 as a means for irradiating excitation light;
Wavelength λ of the excitation light LB from the light source 6₁Only transparent
And the excitation light LB on the surface of the workpiece W
Incident angle θ₁Mirror 8 for irradiating with
A lens 9 for condensing the emitted light on the surface of the workpiece W;
Workpiece W table by the rectangular excitation light LB
Fluorescence L generated from oil 11 applied to the surface _fCondensing
To form a rectangular fluorescent image at the position of the rectangular slit 13.
Fluorescence guided through the optical system 12 and the slit 13
L_f14 that spectroscopy the light with high accuracy,
Fluorescent light L_fFor detecting fluorescence and measuring fluorescence intensity
The light detecting element 15 is provided. Photodetector 15
The measured value of the fluorescence intensity detected in
It is sent to the device 4 and the amount of oil 11
It is calculated.

The optical system 12 emits the fluorescent light L induced on the oil 11 on the surface of the work W by, for example, irradiation of the excitation light LB.
a lens 12a for condensing _f into parallel rays and an interference filter 12b for transmitting a wavelength λ ₂ of the parallel rays
And the fluorescence L _{f of} the wavelength λ ₂ transmitted through the interference filter 12b.
Is combined with a lens 12c that collects light on the surface of the slit 13. In this case, when lenses having the same focal length are used as the lenses 12a and 12c, the excitation light L condensed by the lens 9 on the surface of the work W is used.
Rectangular imaging of B (A ', see FIG. 3) the geometry of the rectangular fluorescent image of the fluorescence L _f which is focused on the surface of the slit 13 (A ", see FIG. 3) be the same as Thus, a fluorescent image can be formed on the slit 13 and efficient fluorescent measurement can be performed.

Reference numeral 17 in FIG. 2 denotes a shutter for blocking light from the excitation light source 6. Reference numeral 18 denotes a slide shutter which is normally closed so as to prevent outside light from entering the inside of the detection head 1 and opened only at the time of measurement, and its opening / closing timing is controlled by the signal control processor 3. Reference numeral 19 denotes a sample fine movement stage for moving the sample holder 2 up, down, left, and right by a fixed length.

The excitation light source 6 has a wavelength of 330 to
Use of a device that outputs (as a rectangular beam) excitation light LB having a wavelength in the ultraviolet region of 350 nm is advantageous because fluorescence having a wavelength of 420 to 450 nm can be obtained with good emission efficiency from, for example, rust-proof oil applied to the work W. It is. However, it is desirable that the oiling amount measuring apparatus of the present invention is compact so that off-line measurement can be suitably performed. In the case of the present invention, the beam shape of the excitation light LB uses a rectangular beam instead of a general circular beam for the reason described later. Therefore, in this embodiment, a commercially available inexpensive and small N ₂ pulse laser oscillator that emits a rectangular beam having a strong peak power and a wavelength of 337 nm is used as the excitation light source 6. Therefore, the wavelength λ ₁ = 33 of the interference filter 7
7 nm. The N ₂ pulse laser oscillator is used as a light source for excitation, and the amount of oil applied to the work W is 100
A rectangular laser beam is condensed by a lens 9 and irradiated on the surface of the work W in a rectangular shape in order to measure with high accuracy in a low oil coating amount range of mg / m ² or less.

[0017] The incidence of the excitation light LB (rectangular laser beam lambda ₁ = 337 nm), the fluorescence L _f is a good laser directivity and monochromaticity induced in oil 11 which is applied to the surface of the workpiece W Light is emitted in a different direction and at a different wavelength from the reflected light (LB ') of the light beam (for example, in the case of a certain kind of rust preventive oil, the wavelength λ ₂ = 435 nm). This is detected by the light receiving optical system 12 arranged in a direction different from the laser reflected light (LB ′), so that highly sensitive detection can be performed. Therefore, in the arrangement of the light receiving optical system 12, the relationship between the incident angle θ ₁ of the laser beam to the work W and the fluorescence reflection angle θ ₂ at which the fluorescence generated by the oil is reflected on the surface of the work W measures the regular reflection. It is preferable to set the relationship so as not to satisfy the relationship (that is, θ ₁ = θ ₂ ). For example, when three-dimensionally arranged under the following condition: 30 ° ≦ θ ₁ ≦ 75 °, θ ₂ = 0 ° (1), fluorescence can be efficiently received and the surface properties of the work W, for example, surface roughness It has been confirmed experimentally that it is hardly affected by the rolling direction, the reflectivity and the like.

Here, the relationship between the shape and size of the excitation light LB which is condensed and applied to the surface of the work W in the present invention, the fluorescent image formed on the slit 13 and the shape and size of the slit 13 In addition, conditions such as arrangement will be described.

The reason why the beam shape of the excitation light LB is rectangular: the accuracy of measuring the amount of applied oil is improved, the irradiation energy is small, and the apparatus can be easily miniaturized as compared with the case of using a circular beam.

This will be described in detail with reference to FIGS. For example, now the fluorescence L focused on the slit 13
_{With respect to} the fluorescent image (beam shape) A ″ of _f , a circular fluorescent beam D ″ having the same energy density per unit area and the same intensity of the fluorescent light guided to the spectroscope 14 is obtained.
And In the case of the circular fluorescent beam D ", although the irradiation area may be small, the irradiation energy may be small. However, the circular fluorescent beam D" may vary due to the unevenness of the surface of the work W to be measured or the distance to the measuring device. The position is shifted and an error is easily generated in the fluorescence intensity, and the measurement accuracy of the amount of applied oil is deteriorated. On the other hand, the fluorescence image of the fluorescence L _f (beam shape)
A ″, the long side length of the fluorescent beam A ′ generated by the rectangular beam of the excitation light LB focused on the surface of the workpiece W (the long side length of the fluorescent image A ″) In the case where a circular fluorescent beam C ″ having a diameter of “C” is used as the diameter, a fluorescence intensity error due to the displacement of the circular fluorescent beam C ″ is unlikely to occur, but the fluorescence intensity received is weakened because the irradiation area is large, and the measurement is performed. Poor sensitivity. Therefore, in order to increase the intensity, it is necessary to increase the irradiation energy, which is not preferable.

Therefore, the beam shape of the excitation light LB of the present invention is rectangular, and the rectangular fluorescent fluorescent image A ″ is focused on the slit 13, thereby displacing the fluorescent image due to the surface condition of the work. Errors are less likely to occur, and the irradiation energy is small.

With respect to the mutual positional relationship between the excitation light, the fluorescent image, and the rectangle of the slit: The beam shape A of the excitation light LB output from the excitation light source 6 composed of an N ₂ pulse laser oscillator is as shown in FIG. , A long side is a ₁ and a short side is a ₂ . The excitation light LB is condensed by the lens 9 and irradiated on the surface of the work W to form a rectangular image A ′ having a long side a ₁ ′ and a short side a ₂ ′. Where a ₁ : a ₂ = a ₁ ':
a ₂ ′. The fluorescence L _f generated by the irradiation, the lens 12a having the same focal length of the optical system 12, when projected onto the slit 13 is condensed by 12c, the long side a ₁ "=
a ₁ ′, and a rectangular fluorescent image A ″ having a short side a ₂ ″ = a ₂ ′. The shape of the slit 13 is such that the long side is b ₁ and the short side is b ₂
Is a rectangle B. In the present invention, the center of the rectangle B of the slit 13 coincides with the center of the fluorescent image A ″ (center point O), and both rectangles are perpendicular to each other (intersection angle α of the center line = 90 °). In this way, the fluorescence intensity due to the unevenness of the surface of the work W itself and the fluctuation error in the relative position between the measurement surface and the measurement device caused when the work W is mounted on the sample holder 2 of the detection head 1. Since the measurement error can be reduced, the reliability of the measurement value is improved.

FIG. 5 shows the results of a comparative experiment conducted to confirm the effect of orthogonalizing the slit and the fluorescent image. That is, with the center of the rectangle B of the slit 13 and the center of the fluorescent image A ″ being aligned, the intersection angle α is set to 90 °.
Measurement error (absolute value) between the measured value and the oiling amount M when α = 0 ° and the sample position is 0 mm for each of the cases of °, 45 °, and 0 ° (both rectangles overlap in parallel) |
ΔM / M | The scale on the horizontal axis is the sample work W
Is the amount of shift in the front-rear direction from the focal position of the excitation light LB at the position (1). From this result, by arranging the slit 13 and the fluorescent image A ″ perpendicular to each other so that the center coincides with each other, even if the holding position of the work W fluctuates 2.0 mm in the front-rear direction, the measurement error is within 5%. It turns out that it becomes.

The rectangular excitation light L focused on the surface of the work W
Regarding the size of the irradiation shape of B and the rectangular size of the slit 13: In the oiling amount measuring device of the present invention, the size of the rectangular image A ′ of the rectangular excitation light LB focused on the surface of the work W has a short side. It is preferable that the length be in the range of 0.4 to 1.0 mm and the long side be in the range of 1.6 to 4.0 mm. Thereby, even when the oil 11 on the surface of the work W is a point-like oil droplet, the irradiation surface can be widened and the excitation energy can be sufficiently secured. When the length of each side is less than the lower limit, the measurement area is too small for the dot-like coating and is easily affected by uneven oil coating. 6 needs to be increased.

The size of the slit 13 is determined by the spectroscope 1.
It is preferable that the short side is in the range of 0.4 to 0.8 mm from the viewpoints of removing stray light to 4, and securing wavelength resolution and signal intensity. If it is less than 0.4 mm, the signal intensity becomes insufficient, and
If it exceeds 8 mm, the removal of stray light will be incomplete.

In the present embodiment, the size of the rectangular beam A of the excitation light LB emitted from the excitation light source 6 is set to the long side a ₁ = 8.
mm, the short side a ₂ = 2 mm, and the dimensions of the rectangular irradiation part A ′ focused by the lens 9 and focused on the surface of the work W are long side a ₁ ′ = 2.0 mm and short side a ₂ '= 0.5m
m, the size of the fluorescent image A ″ focused on the slit 13 is the same as the size of the irradiation part A ′, with the long side a ₁ ′ = 2.0 mm and the short side a ₂ ′ = 0.5 mm.

(Working Example) A work W in which a rust-preventive oil was electrostatically applied to a cold-rolled steel sheet using the oiling amount measuring device shown in the above embodiment and the oiling amount measuring device by another fluorescence analysis method. FIG. 6 shows the results obtained by measuring the amount of applied oil and comparing the results with the values obtained by analyzing the applied amount of oil by a gravimetric method.

Case 1 (CASE 1) is a value (○) measured by the oil amount measurement device of the present invention. Case 2 (CAS
E2) is a rectangular fluorescent image A ″ formed on the slit 13
And the rectangular slit shape B are parallel (that is, the intersection angle α = 0)
°) is a measured value (●) of a comparative example using an apparatus in which an optical system is arranged so as to satisfy (）).

Case 3 (CASE 3) is a measured value (▲) obtained by a conventional apparatus in which the beam shape of the excitation light LB is circular. As is clear from FIG.
In a small region of / m ² or less, the result (CASE1) according to the present invention can be measured with an accuracy within ± 10%. On the other hand, the comparative example and the conventional example (CASE2,
In the result of 3), the measurement error exceeds ± 10%, and the measurement performance is deteriorated.

In the case of this embodiment, the surface roughness of the cold rolled steel sheet used varies in the range of Ra 0.15 to 1.0 μm. Therefore, according to the oiling amount measuring apparatus of the present invention, it can be said that the measurement can be performed without being affected by the surface roughness (base surface roughness) of the work W.

In the above embodiment, the oil type of the oil to be measured is limited to one type. However, when the oil type is different, the fluorescence efficiency is different. Calibration curves representing the relationship with the amount of applied oil are obtained in advance, and the relational expressions are stored in the arithmetic processing unit 4, so that the calibration curve may be selected and used for each type of measured oil. .

The apparatus and method for measuring the amount of oil applied to a metal material surface according to the present invention can be applied not only to steel plates but also to various non-ferrous fields such as aluminum plates and copper foils. In addition, the apparatus for measuring the amount of oil applied to the surface of a metal material according to the present invention has a small and lightweight configuration, so that it can be easily carried, and by removing the holding device 2, the device can be mounted on a sheet-shaped or coil-shaped metal material surface. Since it is also possible to use the method in which the measurement is performed by pressing, the method can be used not only for offline measurement but also for batch measurement in a line.

[0033]

As described above, according to the present invention,
The amount of oil applied to the surface of the metal material to be measured can be measured with sufficient sensitivity and accuracy with sufficient sensitivity, even if the amount of oil applied per unit area is very small, and it can be measured by simple operations, and work is performed automatically. It is also possible to reduce the load,
The frequency of measurement can be increased, resulting in enhanced quality control, early detection of abnormalities, stable application with the desired amount of oil applied, and at the same time eliminate waste due to excessive application and reduce costs. It works.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing the overall configuration of a device for measuring the amount of oil applied to a metal material surface according to the present invention.

FIG. 2 is a diagram schematically showing a configuration of an embodiment of a detection head used in the present invention.

FIG. 3 is a schematic diagram illustrating a relationship between excitation light, a fluorescence image, and the shape, size, and position of a slit in the present invention.
(A) is a perspective view of a part, (b) is an enlarged view of the slit part.

FIG. 4 is a diagram illustrating a relationship between a slit shape and a fluorescent beam shape according to the present invention.

FIG. 5 is a graph of actually measured values showing a correlation between a positional relationship (crossing angle α) between a slit and a fluorescent image and a measurement error.

FIG. 6 is a graph comparing the measured values of the amount of applied oil between the example according to the present invention, the comparative example, and the conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Detection head 2 Holding device (sample holder) 4 Oiling amount calculation means (arithmetic processing device) 6 Excitation light irradiation means (excitation light source) 12 Optical system 13 Slit 14 Spectroscope 15 Fluorescence intensity measurement means (light detection element)

Claims (3)

[Claims] 1. A surface of a metal material coated with oil is irradiated with a rectangular beam of excitation light having a specific wavelength, and the resulting fluorescence is condensed to form a rectangular fluorescent image at a rectangular slit position. Making the long side direction of the fluorescent image orthogonal to the long side direction of the slit and matching the center of each rectangle, and measuring the intensity of the fluorescent light passing through the slit to obtain the oiling amount. Method for measuring the amount of oil applied to the surface of a metallic material. 2. A means for irradiating a surface of an oil-coated metal material with excitation light of a specific wavelength in the form of a rectangular beam;
An optical system that collects fluorescence from the metal material surface generated by the excitation light and forms a rectangular fluorescence image at a rectangular slit position, a spectroscope that disperses the fluorescence guided through the slit, and A means for detecting the fluorescence separated by the spectrometer to measure the fluorescence intensity, and a means for calculating the amount of oil applied based on the fluorescence intensity; An apparatus for measuring the amount of oil applied to a surface of a metal material, wherein the oil amount is arranged so as to be orthogonal to the long side direction of the image. 3. An apparatus for measuring the amount of oil applied to a surface of a metal material according to claim 2, further comprising a holding device for holding the metal material to be measured at a predetermined measurement position.