What are the techniques of measurement using ultrasonic thickness gauges
Ultrasonic thickness gauge is based on the principle of ultrasonic pulse reflection to carry out thickness measurement, when the ultrasonic pulse emitted by the probe through the object under test to reach the material interfaces, the pulse is reflected back to the probe through the measurement of ultrasonic propagation time in the material to determine the thickness of the material under test. Where the ultrasonic wave can be made to a constant speed in its internal propagation of a variety of materials can be measured using this principle.
Ultrasonic thickness gauge is the latest high-performance, low-power microprocessor technology, based on the ultrasonic measurement principle, can measure the thickness of metal and many other materials, and can be the speed of sound of the material measurement. It can measure the thickness of various pipelines and pressure vessels in the production equipment, monitor the degree of thinning after corrosion in the process of their use, and can also measure various plates and various processed parts.
According to the ultrasonic pulse reflection principle designed thickness gauge can be a variety of plates and a variety of processed parts for measurement, can also be a variety of pipelines and pressure vessels in the production equipment to monitor their use in the process of corrosion after the degree of thinning. Can be widely used in petroleum, chemical, metallurgy, shipbuilding, aviation, aerospace and other fields.
Using ultrasonic thickness gauge for measurement technology
First, clean the surface
Measurement should be removed before the surface of the object to be measured all the dust, dirt and corrosion, eradication of paint and other compound cover.
Second, improve the roughness requirements
Excessive roughness of the surface will cause measurement errors, and even the instrument does not read. Measurement should try to make the surface of the material to be measured as smooth as possible before, you can use grinding, throwing, filing and other methods to make it smooth, but also can use high-viscosity coupling agent, the choice of coarse crystal probe SZ2.5P.
Third, rough machining surface
Rough machining surface (such as lathe or planer) caused by the regular fine grooves will also cause measurement errors, make up for the same method 2, in addition to adjusting the probe crosstalk spacer plate (through the centre of the probe bottom surface of the thin layer) and the measured material fine grooves between the angle, so that the spacer plate and fine grooves with each other.
Make the spacer plate and fine groove perpendicular or parallel to each other, take the readings in the zui small value as the measurement of thickness, can achieve better results.
Measurement of cylindrical surfaces
Measurement of cylindrical materials, such as tubes, oil drums, etc., the choice of probe tandem spacer plate and the axis of the material being measured between the angle is critical. Simply put, the probe will be coupled with the measured material, the probe crosstalk spacer and the measured material axis parallel or perpendicular, along the direction of the measured material axis perpendicular to the slow shake of the probe, the readings on the screen will change regularly, select the readings in the zui small value, as the exact thickness of the material.
Select the probe crosstalk spacer plate and the measured material axis of the intersection of the angle direction of the standard depends on the curvature of the material, the diameter of the pipe, select the probe crosstalk spacer plate and the pipe axis perpendicular to the pipe, the diameter of the pipe is small, then select the pipe axis parallel and perpendicular to the two methods of measurement, take the readings in the zui minuscule as the measurement of the thickness.
V. Composite shape
When measuring the composite shape of the material (such as pipe elbow) can be used 7.4 introduced methods, the difference is to carry out the second measurement, respectively, read the probe tandem spacer with the axis of perpendicular and parallel to the two values, and the smaller one as the thickness of the material at the measurement point.
Sixth, the material's temperature effects
Material thickness and ultrasonic propagation speed are affected by the temperature, if the measurement accuracy requirements are high, the same material can be used in the same temperature conditions of the test block were measured, the temperature of the material to calculate the measurement error, to provide parameters to correct it, for steel, high temperature will cause a large error, can be compensated for this method of correction.
