JPS5831522B2 - Himakunoatsumisokuteisouchi - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION X-rays and other radiation are used to measure the thickness of a coating such as a plating layer applied to a steel plate.

In other words, the above-mentioned steel plate is irradiated with X-rays and the intensity of fluorescent X-rays generated from the plating layer of the coating or the steel plate of the substrate is observed. When measuring the thickness separately,
Conventionally, two devices had to be used and each device had to be installed on the front side and the back side of a steel plate, etc.

Therefore, two radiation sources such as X-ray tubes are required, making the device extremely large and expensive, and there are drawbacks such as the difficulty in taking measures against radiation during school hours.

The present invention eliminates these drawbacks and provides an apparatus that can simultaneously measure the thickness of a coating on both the front and back surfaces of a substrate using only one radiation source.

FIG. 1 is a diagram showing the structure of an embodiment of the present invention, in which coatings 2 and 3 made of plating layers of zinc, tin, etc. are provided on both the front and back surfaces of a substrate 1 such as a steel plate.

In order to measure the thickness of this coating 2.3, a radiation source 4 such as an X-ray tube or radioisotope is placed opposite to the front side of the substrate 1, and the substrate is exposed to radiation r of a constant intensity.
A radiation detector 5 is provided on the back side of the substrate 1 to detect the intensity of the radiation transmitted through the substrate.

In addition, fluorescence X generated from the coating 2 by being excited by the radiation
A detector 6 for detecting rays x1 is disposed opposite to the front side of the substrate, and a detector 7 for detecting fluorescent X-rays X2 generated by excitation of the coating 3 is disposed opposite to the back side of the substrate.

The output of the detector 6 is added to a display 8 which displays the thickness of the coating, the outputs of the detectors 5 and 7 are added to a correction circuit 9, and the corrected output is added to a display 10.

The wavelength of the fluorescent X-rays X, , X2 is 1 of the radiation r.
0 times or more, and the radiation r passes through the substrate and coating relatively easily, but the energy of the radiation r is sufficiently greater than that of the fluorescent X-ray so that the fluorescent X-ray is almost completely absorbed in the substrate. It is selected.

In the above-mentioned apparatus, the fluorescent X-rays X emitted to the surface side of the substrate 1 are generated when the coating 2 is excited while the radiation r passes through the coating 2, as shown in FIG. Let Is be the intensity of the radiation r incident on the film 2, and tl be the thickness of the coating 2, then the intensity 1 of the 3 fluorescent X-rays X detected by the detector 6 is: I 1= f t (tl) Is ・
"...(1) However, since the radiation intensity Is is constant as described above, this relationship is represented by a single curve P as shown in FIG. 3a.

Furthermore, since the radiation r also excites the substrate 1 and generates fluorescent X-rays X1, the fluorescent X-rays are detected and the thickness tl of the coating 2 is measured.
In this case, there is a relationship between the thickness tl and the detection intensity 1 by the detector 6 as shown by the curve P'.

Therefore, the output of the detector 6 is added to an appropriate display 8 and the coating 2
The measurement principle is the same as that of conventional devices.

In addition, since the radiation r has sufficiently large energy as described above, it passes through the substrate 1 relatively easily and excites the coating 3 on the back surface.

Therefore, as shown in FIG. 2, fluorescent X-rays x2 are generated from this coating 3, and the intensity thereof is detected by the detector 7.

However, in this case, since the thickness of the substrate 1 and the coating 2 on the surface are not constant, the intensity of the radiation incident on the coating 3 varies.

The radiation is further absorbed by the coating 3 and the intensity (2) transmitted through the coating is detected by the detector 5.

If the thickness of the coating 3 is t2, and the intensity of the fluorescent X-rays detected by the detector 7 is ■2, then □2=r2(i2) II...
There is the relationship (2).

Curve Q1 in Figure 3. Q2... expresses this relationship with the intensity ■1 of the transmitted radiation as a parameter.

Further, the fluorescent X-ray x/2 of the substrate generated when the vicinity of the back surface of the substrate is excited by the radiation transmitted through the substrate 1 is detected by the detector 7.
It can also be detected by

The relationship of equation (2) above also holds true between the fluorescence X-ray intensity ■2 and the thickness t2 of the coating 3, and in this case, if the transmitted radiation intensity ■ is taken as a parameter, the curve Q'+ + Q '2
It is expressed as...

Therefore, by calculating the ratio between the output intensity (2) of the detector 7 and the output intensity (2) of the detector 5 using the correction circuit 9 and adding it to the display 10, the thickness t2 of the coating 3 can be determined.

As described above, the present invention measures the thickness of a coating on the surface of a substrate by irradiating the substrate with radiation having sufficiently higher energy than the fluorescent X-rays of the coating or substrate to be detected, and at the same time measuring the thickness of the coating on the surface of the substrate. This is used to measure the thickness of the coating on the back side.

That is, since the thickness of the coating on both the front and back sides of the substrate can be measured separately using one radiation source, the apparatus can be constructed in a small size and at low cost, and in particular, protection measures against radiation can be easily taken.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the configuration of an embodiment of the present invention, Fig. 2 is a partially enlarged view of Fig. 1 for explaining the invention in detail, and Fig. 3 is an illustration of the measurement principle of the invention. It is a curve. In the figure, 1 is a substrate, 2 and 3 are coatings, 4 is a radiation source, 5 is a radiation detector, 6 and 7 are fluorescent X-ray detectors, 8,
10 is a display, and 9 is a correction circuit.

Claims (1)

[Claims] 1. A radiation source that irradiates a substrate with a coating whose thickness is to be measured on both the front and back surfaces of the substrate from the front side with radiation of a constant intensity having sufficiently higher energy than the fluorescent X-rays of the coating or substrate; An X-ray detector that detects the fluorescent X-rays of the coating or substrate emitted to the surface side and determines the thickness of the coating on the surface side of the substrate based on the intensity, and a radiation detector that detects the intensity of the radiation that has passed through the substrate. A detector detects the fluorescent X-rays of the coating or substrate emitted to the back side of the substrate, and determines the intensity of the coating on the back side of the substrate by the ratio of its intensity to the intensity of the transmitted radiation detected by the radiation detector. A coating thickness measuring device characterized by comprising an X-ray detector for determining the thickness.