Rulers are widely used in mathematics, measurement, engineering and other disciplines. A ruler with a precise ruler. Rulers are used to measure straightness and flatness by light gap method, and can also be used to check length and size together with measuring blocks. So as to check the height of the boss of the workpiece by using the optical gap method. Before measurement, the dose block consists of two groups of dimensions, one is equal to the maximum limit dimension of the tolerance of the boss height dimension, and the other is equal to the minimum limit dimension. If the former is used to test, the contact between the ruler edge and the boss surface is transparent; In the latter inspection, the contact between the edge of the ruler and the measuring surface of the gauge block is transparent, indicating that the height and size of the boss are qualified. Rulers are usually made of rolling bearing steel, which is a very common tool for measuring length. This kind of stationery is very common, almost every primary school student has it. It is usually used to measure short distances or draw straight lines.
Different materials, such as iron, wood, plastic, etc. A ruler has a certain hardness, otherwise it is a soft ruler. The minimum scale is generally1mm. The scale unit is usually centimeters. Length, common is 1 meter ruler and15cm short ruler, but there is no practical limit, so the length ranges from one centimeter to four or five meters.
There are two kinds of scale lines: top (the scale is at the beginning) and non-top (there is a blank in front of the scale line, about 1 cm). The maximum error is usually less than 0.2 mm. The maximum error is 0. 1mm within 30cm, 0. 15mm from 30cm to 50cm, and 0.2 mm from 50cm to 1mm.. ..