JPS60125513A - Device for measuring plate thickness from above coated film by ultrasonic wave - Google Patents

Abstract

PURPOSE:To measure only the thickness of materials by using the first echo, which is reflected from the rear face or materials through a coated film surface, as a start signal of the time base and measuring the second echo and obtaining its time difference. CONSTITUTION:A vertical probe 1 is arraned on a coated film 2 on an object 4 to be measured through a contact catalyst 3. An echo B1 of an ultrasonic wave 5, which is transmitted from the probe 1 and passes the film 2 and is reflected on the rear face of the object 4 to be measured, and an echo B2 of a part of the echo B1 which is reflected on boundaries between the object 4 to be measured and the film 2 and is reflected on the rear face of the object 4 to be measured are detected by an echo peak detector 12 through an analog converter 11 and etc. The time difference is detected by a read latch memory 14, and a plate thickness is calculated and is displayed on a display part 16.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to the measurement of the thickness of materials, and more particularly to an ultrasonic thickness meter suitable for measuring the thickness of materials below the coating surface of materials having a coating film. .

[Background of the invention]

Conventional methods for measuring plate thickness include methods using ultrasonic thickness gauges,
There is a method using ultrasonic flaw detection, but if the surface of the board is coated, the thickness of the coating film is added, making it impossible to measure the true thickness of the board.

In addition, the electromagnetic ultrasonic flaw detection system (MAGCAST)
Although it is possible to measure the wall thickness from the surface of the coating, it has the disadvantage that it is heavy and has poor workability because the probe incorporates an electromagnet.

[Purpose of the invention]

The purpose of this measurement is to measure the material thickness from above the coating surface to below the coating surface for materials with non-metallic coatings such as paint.

[Summary of the invention]

The present invention uses an ultrasonic thickness meter to measure ivy with a coating film, uses the first signal that passes through the coating surface and is reflected from the back surface of the material as a start signal on the time axis, and calculates the second echo from the back surface. The wall thickness was measured based on the time difference.

[Embodiments of the invention]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The principle and embodiments of the invention will be described below with reference to the drawings.

FIG. 1 shows a vertical probe 1 transmitting and receiving ultrasonic waves 5 to and from a measuring object 4 via a couplant 3 on a coating film 2.

The ultrasonic wave 5ii transmitted from the vertical probe 1 passes through the coating surface, is reflected on the back surface of the object to be measured 4 (CB1), and returns to the probe. A part of this ultrasonic wave does not return to the probe but is reflected at the boundary between the object to be measured and the coating film, producing a second bottom echo (B,).

Figure 2 shows the first bottom echo B1 and the second bottom echo B2.
is observed on a cathode ray tube 6.

The calculation formula for the measurement method is shown below.

(1) Time W after ultrasonic wave input until receiving the first bottom echo
B+ is WB1=vts+V(Tt+Tz)+vtl=2vt+
2VT (2) Time until second bottom echo B2 reception WBz
is WB2 = v ts +V (TI +T*+Ts
+T4) +v ts = 2 v t +4VT(3
) The plate thickness T excluding the coating film is as follows: V: Sound velocity of the coating film V: Sound velocity of the material t=t, =: +lt = t3: Coating film thickness T=TI =
T2='l's: Material thickness FIG. 3 shows a block diagram of the plate thickness measuring device. The synchronization circuit 7 has a time system of I
fl control and is transmitted to the clock counter 13 via the signal circuit 8. Further, ultrasonic pulses are sent from the transmitting circuit 9, received on the back side, amplified by the echo amplifier 10, passed through the analog converter 11, and then detected by the echo peak detector 12 as a first bottom echo B1 and a second bottom echo B2.

The second bottom echo is read and goes to the latch memory 14 to generate a time difference, and then passes through the driver 15 to display the board thickness on the display section 16.

By subtracting the measured material thickness T from the beam path distance W B 1 to the first bottom echo B1, the transit time of the coating film thickness can be determined. Knowing the speed of sound in a paint film is effective in measuring the thickness of the paint film.

〔Effect of the invention〕

According to the present invention, even if the object to be measured has a non-metallic coating such as paint, the thickness of the plate excluding the coating can be measured, so there is an effect that the situation of thinning can be grasped without removing the coating.

[Brief explanation of the drawing]

FIGS. 1 and 2 are principle diagrams of a method for measuring true plate thickness from above a coating film by vertical flaw detection, and FIG. 3 is a block diagram of the plate thickness measuring device. 1...Vertical probe, 2...Painted film, 3...Coupling material, 4...Measurement object, 5...Ultrasonic wave, 6...Cathode ray tube, 7...Synchronized generation device, 8...signal circuit, 9.
... Transmission circuit, 10... Echo amplifier, 11... Analog converter, 12... Echo peak detector, 13.
... Clock counter, 14 ... Read latch memory, ] 5 ... Dryno (, #1 Eyes 2 eyes jI 3 Mouth t Continued from page 1 [Phase] Inventor Black 1) Iwao Hitachi Heavy Industries, Ltd.

Claims (1)

[Claims] 1. Transmission circuit, probe, echo amplifier 1. In an ultrasonic thickness gauge consisting of a time axis circuit and an indicator, the first backside echo that passes through the coating surface and is reflected from the backside of the material is used as the time axis start signal. An apparatus for measuring plate thickness from above a coating film using ultrasonic waves, characterized in that the second echo from the back side is measured and the wall thickness is measured from the time difference.