JPS60164202A - Thickness measuring method of double layered materials - Google Patents

Abstract

PURPOSE:To simplify the measurement and to avoid necessity of a highly skilled measuring person, by obtaining the thickness of each layer of the double layered materials from the total thickness measured by the expression of relation, which is obtained by a radiation transmitting method, and a method other than the radiation transmitting method. CONSTITUTION:Radiation, whose radiation intensity is I0, is transmitted through laminated materials 1 from a radiation source 2. Radiation intensity It is detected by a radiation detector 3. The degree of the transmission in the case of the double layered steel plates is expressed by the expression I , where rho1 and rho2 are the densities of the materials, mum1 and mum2 are mass absorption coefficients and t1 and t2 are thicknesses. The total thickness t0 is measured by laser distance meters 4 and 4' and the expression II is obtained. By solving the simultaneous equations of the expressions I and II, the thicknesses t1 and t2 of the layers are obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a method for measuring the thickness of each layer of a two-layer laminate made of different materials, such as a two-layer steel plate, based on a radiographic method. [Technical background of the invention and its issues] In recent years, two-layer steel plates consisting of different material layers on the front and back have become popular. As technology continues to grow, there is an increasing demand for non-destructive measurement of not only the total thickness of two layers but also the thickness of each layer. Conventionally, when measuring the thickness of each layer,
Ultrasonic waves are incident on one surface of the double-layer steel plate, and the incident surface,
Then, the reflected waves from the interface between the two layers were observed, and the time (T) from when the ultrasonic wave was incident until it reached the interface, and the sound velocity within that layer, which had been measured in advance using a test piece. <
From V), from the relationship thickness = TXV, calculate the thickness of one layer on the Okawa side, and calculate the thickness of the other layer by performing the same operation from the other surface, or by using another method to calculate the thickness of the other layer. It was calculated by subtracting the thickness of each layer determined by the L distribution method from the total thickness. However, with this method, reflection of ultrasonic waves occurs not only at the interface between the two layers but also at other locations, so it is difficult to extract and distinguish the waves reflected from the interface from among various reflected waves, and it requires a high level of skill. It took. Furthermore, since this sonic wave method is a contact measurement method, it cannot be applied to objects that move at high temperatures or at high speeds. Additionally, as previously proposed in Japanese Patent Application No. 58-116700, the present applicant has developed a method for measuring the thickness of each material in a laminated material made of different materials by the γ-ray transmission method.
This method has the advantage that the thickness A111 can be determined in a non-contact and non-destructive manner. However, this method uses γ-rays of n (n-2, corresponding to this method) types of energy for n (n=2, corresponding to this method) layers of material;
It is calculated by measuring n times (corresponding to this method, n=2), and there is a problem in terms of ease of use. [Objective of the Invention 1 The present invention has been researched and developed in view of the above-mentioned problems, and its purpose is to measure high temperature or All high-speed moving objects can be handled non-destructively! The object of the present invention is to provide a method for measuring the thickness of a two-layer laminate using a radiation transmission method, which can easily measure the thickness of each layer of the two-layer laminate. [Summary of the Invention] The gist of the method of the present invention for achieving this purpose is as follows. Thickness tl + A2 of each layer of a two-layer laminated material made of different materials: The relationship of the following formula ■ obtained by detecting the transmitted radiation intensity Ito incident on a two-layer laminated material at a certain radiation intensity ■0, and 9-1+ "ρ1" tl+p-mzeρ2° A2
(Here, Jj, Ilt + JL Ilz is the mass absorption coefficient of each material, and ρ1.ρ2 is the density of each material.) The total thickness t of the two-layer laminate material is determined by a method other than the radiographic method.
The following (relationship of Φ formula and t□+t2 obtained by measuring o)
＝to・No. 11 In view of the difficulty and lack of accuracy in distinguishing between waves, we adopted the radiographic method and
In addition, as in the prior invention, measurements are complicated in the gamma ray transmission method with two different intensities, so in order to avoid this, the thickness relationship of each layer can be obtained by only one radiation transmission with a certain intensity, and the total thickness This method takes advantage of the fact that it can be obtained by other simple means rather than the radiographic method. 1 Specific Example 1 of the Invention The present invention will be described in detail below with reference to the drawings. Reference numeral 1 denotes a laminated material, for example, a two-layer steel plate made of two materials, materials a and b, on one of which a radiation source 2 that generates radiation is disposed, and on the other side a radiation detector 3 is disposed. The radiation from the radiation v2 is transmitted through the laminated material l, and the radiation transmitted #11 is detected by the radiation detector 3. Incidentally, the degree of radiation penetration through a material is expressed by equation (1) using the thickness density of the material, the energy of the radiation, and the mass absorption coefficient determined by the type of material. It=Ioe-""ρ"---(1) where Io; Radiation intensity before passing through the material t; Radiation intensity after passing through the material t; Thickness of the material ρ; Density of the material wffi; Mass absorption coefficient The degree of transmission in the case of a double-layered steel plate as shown in Figure 1' is determined by the density of each material being ρ1.ρ2, the quality 1jl absorption coefficient being I' l111 * JL1112, and the thickness being t+.
, tz, it is expressed by equation (2). I to= I oe−” ” °ρ1 ° 1. +
u 1+2 Φρ2◆ A2)...(2) Further (2)
Transforming the equation into equation (3) LL"ps"ts + meL102@ρ2"t2 Also, if the total thickness is to, then to-tl + h...(4), and if to is known, then (3) tw and h can be determined by solving the simultaneous formulas of equations (4) and (4).By the way, to measure to, as shown in Figure 1, in parallel with the measurements of radiation Io and Ito, The thickness to can be measured by measuring the distance from there to the surface of the two-layer laminated material using a laser rangefinder 4.4 degrees installed at a predetermined position, or by using ultrasonic waves, microwaves, etc. Depending on the method used, the distance can be measured by measuring the distance on the front and back surfaces of the clad steel plate, or if the steel plate is in a static state, it can be measured by a mechanical method using a micrometer etc. In this way, the total thickness to can be directly measured as a thickness without using radiation, so there is no need to measure using two types of γ-ray intensities as in the previous method, and this becomes a simpler method. [Example 1] According to the method of the present invention, for a two-layer steel plate in which the material of the first layer is steel and the material of the second layer is aluminum, as radiation,
The thickness of each layer was measured using gamma rays whose energy was 0.8 MeV. The density and mass absorption coefficient of each layer are as follows. /) i -7,85g/ C1n', Jl-11+
-0,0762cm'/gρz -2,70g/c
m', JLat = 0.0777 cm''/g Radiation intensity Io before passing through this double layer steel plate = 41800
cps, radiation intensity after transmission I t = 20H4cp
It was s. The total thickness of the two layers was measured using two laser distance meters and was found to be 1.5 cm. Therefore, by substituting the above values into equations (3) and (4), the following equations are obtained. 0.5982 t+ +0.2098 h” 0.7
0315 + t2= 1.5 The value obtained by solving this simultaneous binary equation is 11. By the way, as a result of directly observing and measuring the cut surface of the two-layer steel plate used in the criminal case, the thickness of each layer was 1.5 mm for the first layer. The Ocm second layer was 0.5c+i, which was almost the same as the result obtained by this method, and the effectiveness of this method was confirmed. [Effects of the Invention 1] As described above, according to the present invention, the measurement is extremely simple because the measurement is performed by one-time radiographic method with a certain intensity and by other easily measurable total thickness. Furthermore, compared to the conventional method using ultrasound, it does not require a high level of skill on the part of the measurer, and since it is usually a non-contact measurement method, it is possible to measure objects at high temperatures or moving at high speeds non-destructively.

[Brief explanation of the drawing]

FIG. 1 is a detailed explanatory diagram of the present invention. l...Laminated material 2...Radiation source 3...Radiation detector 4,4°...Laser distance meter patent applicant Sumitomo Metal Industries, Ltd.

Claims (1)

[Claims] (1) Thickness t of each layer of a two-layer laminate made of different materials! . 1z: The relationship of the following formula (■) obtained by detecting the incident and transmitted radiation intensity Ito of a two-layer laminated material using a certain radiation transmission method 0, and ILlII ・ρ8・ tI+ ILllz ・ρ2・
t21o ゛11n-111111------Brass 111,
--...ku1()It. (Here, JL m+ and μm12 are the mass absorption coefficients of each material, and ρ! and ρ2 are the density of each material.) The following ( The Jllll method for determining the thickness of two-layer laminates is characterized by the relationship of the equation 0 and the measurement from j+ tz = toe m a (?+).