JPS60105907A - Ultrasonic thickness meter - Google Patents

Abstract

PURPOSE:To enable the measurement of a thin article to be measured, by emitting ultrasonic waves having different frequencies while respectively detecting reflected waves from the surface and bottom surface of the article to be measured by first and second detectors and operating both detection values on the basis of a specific formula to calculate a thickness. CONSTITUTION:Ultrasonic waves having frequencies f1, f2 are successively emitted from a probe 1 under the control of CPU 7 and a surface reflected wave is detected by a first power detector 2 while a bottom surface reflected wave is detected by a second power detector 9 and both detection values are subjected to A/D conversion to be stored in memory 8. On the other hand, alpha (the ratio of surface reflected wave power with frequency f1 and bottom surface reflected wave power) and beta (the ratio of surface reflected wave power with frequency f2 and bottom surface reflected wave power) are substituted for formulae I , II to calculate acoustic impedance rhoc and a thickness (d). Subsequently, the thickness (d) is displayed by a display part 6.

Description

[Detailed description of the invention] [Technical field of invention] This invention relates to an ultrasonic thickness gauge.

[Prior Art and Disadvantages] A conventional ultrasonic thickness gauge is configured to measure the echo time of pulsed ultrasonic waves of a single frequency. Therefore, in order to obtain high resolution, it is necessary to have a means that can emit ultrasonic pulses with a high frequency of several Mllz to several tens of Mtlz and a high-speed counter, which has the disadvantage that it is difficult to measure the thickness of thin objects to be measured. .

[Purpose of the Invention Therefore, the purpose of the invention is to transmit ultrasonic waves of different frequencies to
An object of the present invention is to provide an ultrasonic thickness measuring device that can measure the thickness of a thin object by using two or more.

[Configuration and effects of the invention] This invention uses beam-shaped ultrasound waves of different frequencies,
After the ultrasonic waves are reflected by the surface and bottom of the object, the power of each reflected wave is memorized, and the thickness of the object is measured based on the stored power by the calculation means. This makes it possible to measure the thickness of a thin object without using an element that generates high-frequency ultrasonic waves or an element that measures high-speed time. can be provided.

(Explanation of Examples) An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows a block tiagelum which has been subjected to ultrasonic thickness cutting according to the present invention. 1 is a probe, 2 and 9 are power detectors, 3 is a transmitter, and 4 is an A/D conversion control that can generate ultrasonic waves of different frequencies. . Assume that 1 probe 1 is mounted perpendicularly to the object to be measured.

(It is assumed that the acoustic impedance of the probe that touches the object to be measured is measured and known in advance.) The ultrasonic generator 5 transmits ultrasonic waves of frequency f1 to the probe 7- in accordance with the instructions of the CPU 7.
1, and the first power detection unit 2 immediately detects the power of the reflected wave from the surface. The detected power is A
The signal is A/D converted by the /D converter 4 and temporarily stored in the memory 8 via the CPU 7. Next, the second power detection section 9 detects the transmitted wave power that is reflected from the bottom surface of the object to be measured and transmitted through the object to be measured. Furthermore, this power is also A/D converted by the A/D converter 4 and stored in the memory 8. The same operation is performed for ultrasonic waves of a further different frequency f. As a result, equations (1) and (2) are obtained.

F=(ρc, d, f1)-α・G(ρc, d, fl)・
...(1) F = <oc, d, f2) = β・G
(, QC, d, f2)・t2) Here, E and G are functions that are known theoretically in advance, ρC is the acoustic impedance of the measured object, d is the thickness of the measured object, fl and f2 is the frequency of the ultrasonic wave, α is the ratio of the power of the surface reflected wave when an ultrasonic wave with a frequency of 1 is reflected from the surface of the object to be measured, and the power of the bottom reflected wave when reflected from the bottom surface, and β is the frequency This is the ratio between the surface reflected wave and the bottom reflected wave of the f2 ultrasonic wave.

By solving equations (1) and (2) above as simultaneous equations, it is possible to determine the impedance ρG and the thickness d. The requested thickness d is then displayed on the display section 6.

[Brief explanation of the drawing]

FIG. 1 shows a block tie gellum of an ultrasonic thickness gauge which is an embodiment of the present invention. 1... Probe, 2... First power detection section, 4...
・A/D converter, 5... Ultrasonic generator, 7... CP
tJ, 8...Memory, 9...Second power detection section. R revision applicant Tateishi Electric Co., Ltd.

Claims (1)

[Scope of Claims] A means for emitting beam-shaped ultrasonic waves with a low frequency; a second power detecting section that detects the power of the repulsive wave that the iIA sound wave reflects on the bottom surface of the object to be measured; /D conversion Δ/D conversion T
A memory for storing the Δ/D converter outputs of stages and
a calculation means for calculating the power detection value of the first power detection section and the power detection value of the second power detection section based on a predetermined formula based on the different frequencies stored in the first power detection section; An old ultrasonic door that is characterized by measuring the thickness of the object to be measured.