Four elements of geometric measurement
any complete measurement process includes four aspects: the measured object, the unit of measurement, the measurement method and the measurement accuracy, which are generally referred to as the four elements of the measurement process. The structure of the measured object, especially the measurement equipment characteristics and measurement requirements in many fields, determines the measurement method to a great extent. Measurement method refers to the combination of measuring instruments and measuring conditions used in measurement. Measurement accuracy refers to the consistency between the measurement result and its true value
measured object: including length, angle, shape, relative position, surface roughness, etc. As for the measured parts, the influence of its size, weight, batch, accuracy requirements, shape complexity and materials on the measurement should be considered
if it is light, the component will be burnt out. The unit of measurement refers to the standard quantity used to quantitatively represent the same quantity value. Among the legal units of measurement issued by China, the basic unit of length in geometric quantities is meters (m), and the angle unit of plane angle is radians (RAD) and degrees, minutes and seconds. In mechanical manufacturing 6 The friction force of the force measuring piston in the oil cylinder increases or gets stuck. Mm is often used as the measurement unit, and micron (UM) or even nanometer is used in precision measurement
measurement method: measurement method refers to using the measurement principle and actual operation in actual measurement according to the given measurement principle to obtain measurement data and results
measurement accuracy: refers to the degree that the measurement result of the measured geometric quantity is consistent with its true value. In the process of measurement, due to the influence of various factors, large or small measurement errors will inevitably occur. If the measurement error of 8 items of elastic modulus and maximum experimental force is small, the measurement accuracy is high, and if the measurement error is large, the measurement accuracy is low
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