SU994911A1 - Method of ultrasonic measuring of moving object thickness - Google Patents

Description

(five)

METHOD OF ULTRASONIC MEASUREMENT OF THICKNESS OF MOVING PRODUCT

The invention relates to measurement technology and can be used for continuous contactless measurement of the thickness of moving products made from materials with a high attenuation coefficient of ultrasonic vibrations.

A known resonant method for measuring the thickness of a product is that it generates ultra sonic oscillations, receives them reflected from the reflector, records the resonant frequency of the transducer-product system and judges the thickness of the product being monitored. Measurements are carried out in a contact variant of the joint venture.

The disadvantage of this method is the low accuracy of measuring the thickness of the product from the LII of materials with a large attenuation coefficient of ultrasonic vibrations, since it uses the acoustic characteristics of the device itself.

product, and a large damping in the material of the product does not allow a clear resonance of the system.

An interferometric method for measuring the thickness of a product is known, which consists in sounding a controlled product, which is located between the emitter and the reflector, receive the signal by a microphone located in the acoustic channel, determine the phase of the standing wave, sum the reference signal from the generator and the signal proportional to pressure in wave 2.

Claims (3)

The disadvantages of the interferometric method for measuring the thickness of a product are the limitations of its functionality due to the discreteness of the output information, and the comparatively low accuracy of measuring the thickness of products due to the influence of their dimensions on the measurement accuracy of the characteristics of the sound field. 3 The closest to the technical essence of the present invention is a method for measuring the thickness of a moving article, which consists in voicing the product under test from two sides using mutually aligned searchers, receiving signals reflected from their surfaces and determining the thickness of the product. Sound are in pulsed mode G 3. The disadvantages of the method are the comparatively low accuracy of measuring the thickness of the product made of viscoelastic material, and the complexity of the instrumental implementation of the method, due to the presence of an additional channel for comparing ultrasonic vibrations. The purpose of the invention is to improve the accuracy of measuring the thickness of an article made from a visco-elastic material. The goal is achieved by the fact that sounding is carried out in a continuous mode by the emitter and receiver of each searcher located in the same plane parallel to the product surfaces at a distance H, respectively, from the nearest surface selected from the ratio I 7, H, (2n - 1) - A is the radiation wavelength; n is an integer defined by the expression. N Р + 2 (Dn + d) 2 D tg ot where DM is the diameter of the Emitter; Dfi is the diameter of the receiver; c is the gap between the emitter and receiver; c (- radiation divergence angle depending on the parameters of the emitter and the medium. The drawing shows a device for implementing the method. The device contains separately aligned searchers 1 and 2, having emitters 3 and i, and receivers 5 and 6, generator 7 of ultrasonic vibrations The processing and recording unit 8 contains 4 two transducer amplifiers 9 and 10, a true thickness thickness unit 11 and a unit 12 for setting the nominal thickness of the product 13, the method is as follows. are placed on the initial distance H from the corresponding plane of the tested product 13 and parallel to it. The nominal thickness of the product is set in block 12. The oscillator 7 of ultrasonic vibrations operating in continuous mode excites the emitter 3 of the separately-combined finder 1 so that formed between the nearest surface of the test article 13 and the corresponding plane of the searcher 1, a standing ultrasonic wave was established. The zero value (origin) of the output signal of the receiver is taken as its average value, which is proportional to the average value of the standing wave pressure on the plane of the receiver at the location of the separately-combined finder at the initial distance H from the corresponding surface of the product. The receiver signal L is fed to the output of the amplifier-converter 9, where amplification, detection and conversion of the signal to the code takes place. Using the converter amplifier 9, the code value corresponding to the average value of the receiver output signal at the initial distance H is compensated, and the magnitude and sign of the output code deviation relative to the average is determined. This signal is then fed to the input of the true value block 11. Similarly, reception and processing of a duplex finder signal is provided. 2. In block 11 of the true thickness value, the code of its nominal value obtained from block 12 is summed up with the code values of the thickness deviation from the nominal value, taking into account their signs, which came from blocks 11, the true value of the article under test is determined and recorded. This method improves the accuracy of measuring the thickness of products made from viscoelastic material. The invention The method of ultrasonic measurement of the thickness of a moving product, which consists in that the controlled product is voiced from two sides c. using split-matched searchers, they take the signals reflected from its surfaces, and from them determine the thickness of the product, that is, in order to improve the accuracy of measuring the thickness of the product made of viscoelastic material, in the continuous mode, I place the emitter and receiver of each searcher in one plane parallel to the surfaces of the device at a distance H, respectively, from the nearest surface selected from the ratio n xHK2n-f) - i, l / / i {L / 1 I 6 and 6 where L is the wavelength of the radiator; h is an integer determined from the expression Вм-2 () (1)) V where DM is the diameter of the radiator; Op is the diameter of the receiver; cf- - the gap between the emitter and receiver; oL is the angle of divergence of the radiation, depending on the parameters of the radiator and the medium. Sources of information taken into account in the examination 1. The author's certificate of the USSR W 1799, cl. G 01 B 17/02, 19652. Kolesnikov A.E. Ultrasonic measurements. M., Energie, 1970, p.50 3. Authors certificate of USSR 485377, cl. G 01 B 17/02, 1971 (prototype).