Pneumatic pneumatic - valve Working principle of the ultrasonic thickness meter and reasons affecting the accuracy of measurement

ultrasonic thickness meter: according to the working principle of the points of interference method, resonance method and pulse reflection method, due to the pulse reflection method does not involve the resonance mechanism, not correlated with the degree of finish on the surface of the object to be tested, so ultrasonic thickness meter pulse method is one of the most popular with the users of the instrument. 。 Working principle of the ultrasonic thickness meter mainly host and probe of two parts. Host circuit including counting emission circuit, receiving circuit, display circuit three parts, high pressure shock wave produced by firing circuit incentive probe, produce ultrasonic transmitted pulse wave, pulse wave after the medium interface reflection was receiving circuit to receive, by single-chip microcomputer count after processing, the thickness of the LCD display, it is mainly based on sound wave propagation velocity is multiplied by the sample time in the sample the half of the thickness of the specimen. The launch of the ultrasonic pulse when the probe through the material object to be tested interface, the pulse is reflected back to the probe, through the accurate measurement of ultrasonic wave propagation in the material time to determine the thickness of the material being tested. Jining Mr Tai ultrasonic measuring thickness meter AT series is the collection of contemporary science and technology, electronic technology and measurement technology in the integration of advanced nondestructive testing instrument, using highly optimized measurement circuit, with high measurement precision, wide range, simple operation, stable and reliable work, etc. Those that make the ultrasonic wave at a constant speed in its internal communication of various materials on the principle of the measurement. Can accurately measure about all kinds of plank and machining parts, widely used in petroleum, chemical industry, metallurgy, shipbuilding, aviation, aerospace and other fields. 。 Reason affect the measurements accuracy of triangulation: ultrasonic thickness meter clean surface measurement should remove all the surface of the object to be tested before dust, dirt and rust, remove paint covering, etc. Improve roughness requirement too rough surface will cause measurement error, even without reading instrument. Before measurement should try to make the measured surface is smooth, can use methods such as grinding, polishing, file to make it smooth. High viscosity of coupling agent can also be used. Measuring the temperature of the material influence the thickness of the material and ultrasonic wave propagation velocity are affected by temperature, if the measurement accuracy is high, can use block contrast method, which USES the same block of material at the same temperature conditions was measured, and temperature compensation coefficient is obtained, and the coefficient of correction measured values of the measured workpiece thickness gauge and test block of different material under different conditions to carry on the accurate measurement, the calibration block material more close to the material being tested, measurement is more precise. The ideal reference block is a set of measured materials of different thickness of the block, block can provide instrument compensation correction factor ( Such as the material microstructure, heat treatment conditions, the particle direction, surface roughness, etc. In order to meet the requirement of maximum precision measurement, a set of test piece will be very important. In most cases, as long as the use of a reference block can get satisfactory accuracy of measurement, the block should be the same as the material under test of similar material and thickness. Apply evenly after the material being measured with micrometer to measure can be as a block. For thin material, in its thickness is close to the probe measuring limit, available test blocks to determine accurate low limit. Don't measure below the lower limit of the thickness of the material. If a range of thickness can be estimated, then the thickness of the block, choose the threshold value in certain cases, the look up table of the sound known material, can block instead of a reference, but it is approximate to replace some reference blocks, in some cases, the speed of sound in the table different value and the actual measurement, this is because the materials have different physical and chemical conditions. This method is often used to measure low carbon steel, but only as a rough measure.
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