JPH03272439A - Method and apparatus for measuring rustproof oil coating amount on steel plate - Google Patents

Abstract

PURPOSE:To accurately measure a rustproof oil coating amount by branching a reflected light from a steel plate, selectively detecting the intensities of lights of an excited wavelength region and a fluorescent wavelength region, and correcting the intensity of the received light of the fluorescent wavelength region by the surface state of the plate according to the information. CONSTITUTION:The surface of a steel plate 3 continuously fed and coated with rustproof oil is emitted with a luminous flux 2 of specific exciting wavelength from a light source 1. Reflected lights from the plate 3 are condensed by a condensing lens 4. The condensed reflected light is guided to a light dividing element 5 to be branched to luminous fluxes 2a, 2b. The flux 2a is guided to a spectral element 8 and detected at the intensity of an exciting wavelength region by a photodetector 6. The flux 2b is guided to a spectral element 9 and detected at the intensity of a fluorescent wavelength region by a photodetector 7. A calculator 10 corrects the received intensity of the fluorescent wavelength region by the surface state of the plate 3 by the outputs of the photodetectors 6, 7 and calculates the quantity of coating oil of the plate 3.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method and apparatus for measuring the amount of rust preventive oil applied to the surface of a steel plate, and in particular, on-line quality control in the cold rolling process and surface treatment process in the steel industry. The present invention relates to a measuring method and apparatus suitable for application to control of the amount of oil applied and capable of measuring the amount of rust preventive oil applied on the surface of a steel plate with high accuracy.

Conventional technology In general, the surfaces of cold-rolled steel sheets and various plating materials manufactured through processes such as cold rolling and surface treatment are coated with anti-rust oil to prevent rust from forming. This anointing method is
Usually, a continuous oil application method using an electrostatic oil application device is common.

However, in this continuous oil application method, the rust prevention effect is reduced due to an insufficient amount of rust preventive oil applied and uneven oil application, and conversely, an excessive amount of oil applied causes the raw material of rust preventive oil to deteriorate. Problems arise such as an increase in the number of units and the occurrence of unmetallic parts due to insufficient degreasing. -Since the capabilities of users' degreasing equipment vary, recently there are many cases in which the type and amount of anti-corrosion oil to be applied are individually specified. Control of application amount is required.

However, the main method of controlling the coating amount is off-line batch measurement using sampling, and this control method has the following problems.

The coating amount is mainly measured by, for example, a gravimetric method using a precision balance, a hydrofil balance method in which the coating amount is calculated from the area of a monomolecular layer of oil formed on the water surface, or the like. However, in the former gravimetric method using a precision balance,
If the amount of oil applied is small, such as about 1100II/m2,
WJ density is poor and the latter hydrofill balance method
There is a problem that measurement requires a long time. In addition, all of these methods are offline measurement methods,
Measurements are only made at one to several points in the rolled coil, and each measured value does not necessarily represent the representative value of the entire length of the coil, making it extremely difficult to adjust the coating amount. .

Therefore, various online measurement methods have been proposed to overcome these drawbacks.

As one of such online measurement methods, for example, Japanese Patent Application Laid-Open No. 63-61146 discloses that excitation light 1'llt from a mercury lamp, e.g., 253, 77
A method has been proposed in which the rust-preventive oil adhesion amount is calculated by irradiating the surface of the steel plate with anti-corrosive oil (nm) and measuring the amount of fluorescence generated from the fluorescent substance contained in the oil. Although it has been confirmed that this method provides sufficient sensitivity,
In processes where the amount of coating is small, such as 100 JI or '12100, the reflected acid content of the base is large, and measurement errors occur due to changes in surface properties such as surface roughness and gloss, which vary from coil to coil, so it is necessary to perform stable measurements. is difficult.

Furthermore, in Japanese Patent Application Laid-open No. 138102/1982, excitation laser light of a specific wavelength is applied to the surface of a steel plate coated with anti-rust oil.
At this time, secondly, one of the fluorescence spectra generated from the steel plate surface. A method has been proposed in which the intensity of the fluorescence spectrum contained only in oil is detected and the amount of oil applied is determined from the intensity of this fluorescence spectrum. However, with this method, it is necessary to install an online roughness meter upstream of the line, and in the case of steel sheets with the same roughness but different surface properties such as gloss, the detected fluorescence spectral intensity is affected by changes in surface properties, resulting in errors in measured values.

Problems to be Solved by the Invention The present invention has been made to solve the above-mentioned problems, and in particular, the above-mentioned online measurement method is affected by the surface properties of the base steel plate, The purpose is to solve the drawback that the coating amount cannot be measured with high precision.

Means for solving the problem and its effect. As mentioned above, in the oil coating amount measurement method described in JP-A-61-138102, the fluorescence spectrum intensity is affected by changes in the surface properties of the steel sheet. Therefore, we conducted experiments and studies to eliminate this effect. As a result of this experiment, the reflection spectrum generated from the steel sheet surface includes excitation photoacid components in addition to the fluorescent acid component of the oil, and since the excitation light wavelength and fluorescence wavelength are close to each other, the spectrum in the fluorescence wavelength region It was found that the intensity is not only the spectral intensity of fluorescence but also includes the fluorescence amount wi and components of the excitation light.

It has also been found that the amount of excitation light included in this fluorescent wavelength region varies depending on the surface condition of the underlying steel plate, and in particular, the light intensity in the fluorescent liquid required region varies depending on the surface condition. Furthermore, the intensity of the excitation light component included in the fluorescence wavelength region has a correlation with the excitation light intensity change in the excitation light 'tL long region. It was found that although the absolute value of intensity changes, the intensity ratio is maintained.

Therefore, from these results, it is possible to calculate the amount of excitation light included in the fluorescence wavelength region from the relationship between the intensity of the excitation light wavelength region and the fluorescence wavelength region in the reflection spectrum of the steel plate surface, and the amount of excitation light included in the fluorescence wavelength region can be calculated. It can be seen that by subtracting from the total strength, the amount of oil applied can be calculated with high accuracy, removing the influence of the surface condition.

In other words, the gist of the present invention is to irradiate the surface of a steel plate coated with oil with excitation light of a specific wavelength, to split the resulting reflected light from the steel plate surface using an optical element, and to separate these branched reflected lights. Excitation light 'l from one of the reflected lights
Selectively collect the intensity of the l-length component, collect the intensity of the fluorescence wavelength region from the other reflected light, and from the results of these collections, use the information obtained to calculate the intensity of only the fluorescence with the influence of the surface condition removed. Calculate and on the steel plate! l! This is a method and device for measuring the amount of oil applied to the surface of a steel plate to determine the oil action with high precision.

Next, the structure of these means and their operation will be explained in more detail as follows.

First, in measuring the amount of oil applied to the surface of a steel plate according to the present invention, the surface of the steel plate to which this oil has adhered must be
1-length excitation light is irradiated, the reflected light generated by this irradiation is split by an optical element, the reflection intensity change in the excitation light wavelength region is measured for one branched reflected light, and the reflected light for the other branched reflected light is measured. Measures the intensity of the oil's fluorescence wavelength range.

In other words, the reflected light obtained by irradiating the oil-covered steel plate surface with excitation light of a specific wavelength, that is, the reflection spectrum, does not simply consist of the fluorescent acid content of the oil, but as shown in Figure 2. In addition to the fluorescent acid content of the oil, it also contains an excitation light component, and the intensity of the excitation light is very strong, with wavelengths close to each other. Therefore, the intensity in the fluorescence wavelength region is the sum of the oil fluorescence component and the excitation light component. Furthermore, this excitation light component is similar to the surface of the underlying steel plate! 9 varies depending on the detection angle due to the difference in light scattering distribution.

However, as mentioned above, this amount of change is experimentally
It was confirmed that there is a correlation between the excitation light intensity in the excitation light wavelength region and the excitation light intensity included in the fluorescence wavelength region.
In particular, even if oil adheres to a steel plate, even if the absolute value of the intensity differs due to the absorption of light by the oil, this correlation is expressed as II, and it is not necessary to directly calculate the excitation light intensity included in the fluorescence wavelength region. ,fluorescence'! The excitation light intensity included in the l region can be accurately determined by measuring the excitation light intensity in the excitation light region.

That is, by applying rust preventive oil to a steel plate with a small roughness and a steel plate with a large roughness, and changing the value Im, the excitation light intensity in the excitation light region becomes the excitation light intensity included in the fluorescent liquid region as described above. Using the correlation between the fluorescence 'lI
The received light intensity of l chain length and the excitation light intensity included in the fluorescence 'tL length region were experimentally determined and were as shown in FIGS. 3 and 4. In Figures 3 and 4, the symbol ◆ indicates the received light intensity in the fluorescence wavelength region, and ◇ indicates the intensity of excitation light contained in the fluorescent liquid region. indicates a steel plate with large roughness. When the fluorescence intensity is calculated from these two pieces of information, the fluorescence intensity indicated by the symbol ■ is obtained. More specifically, as shown in FIG. 4, in a steel plate with a large surface roughness, the influence of light scattering is large, and the proportion of excitation light included in the fluorescence wavelength region is large. On the other hand, as shown in Fig. 3, steel plates with a small surface roughness have a relatively small effect of light scattering.
The proportion of excitation light included in the fluorescence wavelength region is small. In either case, by subtracting the proportion of this excitation light, the influence of surface roughness can be removed, and the amount of antirust oil applied on the surface of the steel plate can be measured with high precision.

In short, as is clear from the above, it is not enough to simply measure the intensity in the fluorescence wavelength region, but also to measure the change in the reflected light intensity of the excitation light chain length. The intensity of the excitation light is the same as the surface of the steel plate! II
The fluorescence wavelength gAV1. Since there is a correlation between the excitation light intensity contained in The applied amount of rust preventive oil can be determined with high accuracy while correcting the fluctuations in the excitation light intensity. When the amount of applied oil is determined in this way, even if the amount of applied oil per unit area is minute, it is possible to measure at a sufficient li of 8 degrees.

FIG. 1 is a layout diagram of an oil coating amount measuring device according to one embodiment of the present invention, and this measuring device includes a light source 1 that emits excitation light of a specific wavelength, a condensing lens 4, etc. a light-splitting optical system, a light splitting element 5 for splitting the reflected light collected by the focusing optical system, a spectroscopic element such as a diffraction grating, and each branched reflected light split by the light splitting element 5. Each spectroscopic element 8.9 selectively transmits light, a photodetector 6.7 that detects the intensity of light transmitted through each spectroscopic element 8.9, and detection information from these photodetectors 6.7. It consists of an arithmetic device 10 that performs calculations.

That is, a light beam 2 having a specific excitation wavelength 21 is irradiated from a light source 1 onto the surface of a steel plate 3 that is continuously traveling and whose surface is coated with antirust oil. The reflected light from the surface of the traveling steel plate 3 is condensed by a condenser lens 4. This condensed reflected light is guided to the light splitting element 5, and is divided into at least two light beams 2a,
2b.

Among these branched light beams 2a and 2b, one light beam 2a
is guided to the spectroscopic element 8, where light in the excitation light wavelength region is selectively transmitted, and the light intensity in the excitation light wavelength region is detected by the photodetector 6. Further, the other branched light beam 2b is guided to the spectroscopic element 9, where light in the fluorescence wavelength region is selectively transmitted, and the light intensity in the fluorescence wavelength region is detected by the photodetector 7. The output side of these photodetectors 6.1 is the aI calculation device io
s, - are connected, and the coating amount is calculated by the arithmetic unit 10 based on the outputs from both photodetectors 6.7.

Note that the output side of this performance instrument W110 is connected to the host nose meter 11, and the host calculation 11111 outputs data logging and a feedback signal to the v1 oil device.

Note that the wavelength λl of the excitation light irradiated from the light 111 and the detection wavelength range detected by the photodetector 6.7 are the excitation light wavelength;
+ and by checking the characteristics of each oil type to set it to an appropriate value in advance.

In addition, the excitation wavelength λ1 is set within a range that efficiently emits fluorescence from the substance, and is preferably 0.25 to 0.
．． Ultraviolet to visible wavelengths within the 6 μm range are suitable. With this wavelength, a light-receiving element that receives fluorescence generated upon excitation can be selected to have high detection sensitivity.

Example First, anti-rust oil was applied to a base steel plate with an average roughness of 0.2 to 1.0 μm, and the reflected light was reflected by the method of the present invention using the steel plate while it was running, as shown in Figure 1. The amount of rust preventive oil applied was measured by branching and measuring the intensity of these branched lights. In this case, an Ar laser light source with an excitation wavelength of 476.5 μm is used as the light source 1, a photomultiplier tube is used as the photodetector 6.7 for detecting the intensity of each branched light, and the spectroscopic element 8.9 is selected. The excitation wavelength range is 476.5r.
+Sono ±50-1 Fluorescence wavelength range is 5351'+lI±25
ni+ was used.

When measured using the present invention as described above, it was found that approximately 1
00a+g, -' When rust preventive oil of ra2 is attached,
The results shown in FIGS. 5 and 6 were obtained. That is, FIG. 5 shows the light intensity in the excitation wavelength region detected by the photodetector 6, and FIG. 6 shows the light intensity in the fluorescence wavelength region measured by the photodetector 7. As shown in the table, the amount of rust preventive oil applied was determined with high accuracy.

Further, for comparison, when the coating amount was measured using the conventional example shown in JP-A-61-138102, as shown in Table 1, the variation was large and the standard deviation could not be measured.

Table 1 Furthermore, as described above, when the information on the amount of coating measured by the present invention was fed back to the oil application device by the host computer 11, a more stable quality control system could be realized.

<Effects of the Invention> As explained in detail above, the present invention splits reflected light from the surface of a steel plate coated with anti-rust oil, measures the light intensity of the excitation light region from one branched light, and measures the light intensity of the excitation light region from one branched light. The light intensity in the fluorescence wavelength region is detected from the branched light, and the amount of anti-rust oil applied is determined from this detected information. Therefore, even if the amount of oil applied to the surface of the steel plate is minute, it can be measured with high accuracy.

The influence of surface properties such as roughness and reflectance of the base steel plate is determined by the light intensity of the excitation light region and is sufficiently corrected, so this measuring device can be constructed simply and inexpensively. In short, according to the present invention, in addition to being able to apply oil according to the user's requirements, it is possible to stabilize the quality by eliminating uneven coating,
As expected, significant economic effects can be realized, such as achieving the minimum amount of anti-R oil applied and omitting the off-line oil application measuring work that was conventionally done.

In addition, although the above description has mainly focused on an example in which the present invention is applied to coating a measurement on the surface of a running steel plate in a steel industry line, the present invention can also be applied to any field, for example, various non-ferrous fields. It is possible.

[Brief explanation of drawings]

FIG. 1 is a layout diagram of a rust preventive oil coating amount measuring device according to one embodiment of the present invention, FIG. 2 is a graph showing the characteristics of the spectrum representing excitation light and oil fluorescence, and FIGS. The figures are graphs showing the correlation between the total received light intensity, fluorescence intensity, and excitation light intensity included in the fluorescence wavelength region, respectively. Figure 5 shows the characteristics of the spectrum of the excitation light detected by one photodetector. The graph shown in FIG. 6 is a graph showing the characteristics of the wavelength range of fluorescence detected by the other photodetector. Code 1... light)ll 2...
・Light flux 3... Steel plate 4... Condensing lens 5... Light splitting element 6.7...
...Photodetector 8.9...Spectroscopic element 10...
...'I4 arithmetic drawing device ...... Upper computer #KitlLk, Qwei Figure 2

Claims (1)

[Claims] 1) When irradiating the surface of a steel plate coated with oil with excitation light of a specific wavelength and determining the amount of oil applied on the surface of the steel plate from the spectral distribution of the reflected light generated by the irradiation, The reflected light from the steel plate is split by an optical element, and the light intensity in the excitation wavelength region is selectively detected from one of these branched reflected lights, and the fluorescence wavelength is detected from the other branched reflected light. The amount of rust preventive oil applied to the surface of a steel plate is calculated by selectively detecting the light intensity of the area and correcting the received light intensity in the fluorescence wavelength range depending on the surface condition of the steel plate based on this information. Measuring method. 2) A light source that irradiates the surface of the steel plate coated with anti-rust oil with excitation light of a specific wavelength, a condensing optical system that collects the reflected light from the steel plate surface, and at least two A light splitting element that splits the light beam into two light beams, a spectroscopic element that selects the light in the excitation light wavelength region of one of the branched light beams, and a photodetector that detects the light intensity of the transmitted excitation light wavelength region. a spectroscopic element that selects the light in the fluorescence wavelength range of the other beam, a photodetector that detects the intensity of the transmitted light in the fluorescence wavelength range, and the outputs of both photodetectors are processed to prevent rust. 1. An apparatus for measuring the amount of rust preventive oil applied to a steel plate surface, comprising: a calculation device for calculating the amount of oil applied.