SU857850A1 - Ultrasonic thickness meter - Google Patents

Description

(54) ULTRASONIC THICKNESS METER

The invention relates to a test measurement technique, namely to the excitation and reception of ultrasonic vibrations, and is intended to measure the thickness of electrically conductive media and can also be used to calibrate ultrasonic thickness gauges. A known ultrasonic thickness gauge containing ultrasound transducers associated with a pulse generator, a form amplifier, a data processing unit, and a digital recording ll. A disadvantage of this device is the low measurement accuracy. The closest to the proposed technical entity is an ultrasonic thickness gauge containing a transducer connected to a pulse generator and a force forming device, as well as a digital recording unit and a processing unit including a synchronizer and a time interval counter C2. A disadvantage of the known device is low accuracy and reliability of measurements. The purpose of the invention is to improve the accuracy and reliability of measurements. The goal is achieved by the fact that the converter is made by two electromagnetic waves, the device has an additional pulse generator, a comparator, an adjustable reference time generator, two AND gates, a NAND gate, and the output of the second pulse generator is connected to the second input of the converter, the output Amplifier -former through the logical element AND-NOT and the time interval counter is connected to a digital recording unit connected to an adjustable the reference time generator, the output of which through the comparator is connected to the first inputs of logic elements and whose outputs are connected to pulse generators, the second inputs of logic elements AND are interconnected and connected through a synchronizer to the second input of the logical element IS-NOT and the second output of the counter time intervals connected to the second input of the comparator. On .fig. 1. shows a block diagram of the proposed ultrasonic measuring instrument THICKNESS, FIG. 2 is a time diagram illustrating the operation of an automatic switching device of the type of wave being excited.

Ultrasonic thickness gauge contains synchronizer 1, generators 2 and 3 pulses, logic elements 4 and 5, two-wave electromagnet-acoustic transducer b, located above measurement object 7, amplifier-shaper 8, logic AND 9, time counter iO, comparator li , adjustable generator 12 reference time interval, unit 13 digital registration with,

The device works as follows.

A synchronizer pulse 1 (Fig. 1 and 2) sets the time interval counter 1o and the registration unit 13 into O and starts the generator 2 or J through logic elements 4 or 5, which excites the measurement object 7 using a transducer in an electrically conductive medium, or a shear wave. . Converter 6 receives pulses vi reflected from the object bottom, which, together with a probe amplitude limited in amplitude, arrive at the input of the amplifier-former 8 and the NAND gate, where the reflected pulses are filtered out (Fig. 2). The latter are recalculated by the lO tl counter of measured time intervals, forming a pulse of duration nt (Fig 2}. This pulse controls the counter of the digital recording unit 13 and simultaneously arrives at the first input of the comparator 11 (Fig. 1 and 2) where it compares with the duration the reference time interval tg (arriving at the second input of the comparator il (Figs. 1 and 2). the response time interval is generated by the generator 12, which is a frequency divider of the quartz oscillator, which allows manual adjustment of the time interval, depending on the range of measured thicknesses and ultrasound velocity in the material.

If the interval p t is less than the set reference interval tg corresponding to the minimum thickness of the measurement object with a permissible error, then the comparator 111. produces a signal (Fig. 2), including a generator 3, with which the converter b excites shear waves in the measurement object 7 As a result the measurement error is halved. Otherwise, the comparator 11 generates a signal, including a generator 2, with which the converter b excites longitudinal waves in the object of measurement.

The duration of the reference interval ta is set manually for each measured material by the minimum thickness, the measurement error of which exceeds the maximum permissible for the meter, and the shift;

The proposed ultrasonic thickness gauge is characterized by an increased accuracy, an expanded measurement limit in the direction of small thicknesses, and can be used to measure the thickness of products on untreated, as well as coated with a layer of paint or corroded surfaces, which increases the reliability and performance of measurements and enables automation of measurements.

Claims (2)

1. Lantuh V.M. and others. Ultrasonic portable digital thickness gauge. - Defectoscopy, No. 5, 1977, p. 125-127. 2. Korolev M.V. and others. Portable echo-pulse ultrasonic thickness gauge UT-31 MC. - Defectoscopy, 2, 1917f p. 18-25 (prototype). Fcg.2