What are the methods of measurement?

1, according to whether the measured parameters are measured directly, can be divided into direct measurement and indirect measurement.

Direct measurement: direct measurement of the measured parameters to obtain the measured size. For example, with calipers, comparator measurements.

Indirect measurement: Measurement of geometric parameters related to the measured size, after calculation to obtain the measured size.

2, according to the reading value of the gauge gauge whether the value of the measured size directly, can be divided into absolute measurement and relative measurement.

Absolute measurement: the reading value directly represents the size of the measured size, such as vernier caliper measurement.

Relative measurement: the reading value only indicates the deviation of the measured size from the standard.

3, according to the measured surface and the measuring instrument measuring head contact, divided into contact measurement and non-contact measurement.

Contact measurement: the measuring head and the contact surface contact, and there is a mechanical effect of the measurement force exists. Such as micrometer measuring parts.

Non-contact measurement: the measuring head is not in contact with the surface of the measured part, non-contact measurement can be avoided to measure the impact of force on the results. Such as the use of projection method, light wave interference method of measurement.

4, according to the number of parameters measured at a time, divided into single measurement and comprehensive measurement.

Single measurement; each parameter of the measured part is measured separately.

Integrated measurement: measurement reflects the comprehensive indicators of the relevant parameters of the part. Such as the tool microscope to measure the thread, can be measured separately out of the actual diameter of the thread, tooth half-angle error and pitch cumulative error, etc..

5, according to the role of measurement in the process, divided into active and passive measurement.

Active measurement: the workpiece in the process of measurement, the results are directly used to control the parts of the process, so as to prevent and control the production of scrap.

Passive measurement: workpiece processing after the measurement. This measurement can only determine whether the processed parts are qualified, limited to the discovery and elimination of scrap.

6, according to the measured parts in the measurement process in the state, divided into static measurement and dynamic measurement.

Static measurement; measurement of relatively static. Such as micrometer to measure the diameter.

Dynamic measurement; measurement of the measured surface and measuring head simulation work in relative motion.

Level Measurement Principle

From the zero point of the elevation of the tide gauge station, the method of level measurement to determine the establishment of the tide gauge station near the national design of the level of the origin, as the starting point of the national elevation control network. The origin of the national level was set up in Qingdao, Shandong Province. From the national level origin, the first, second, third and fourth level measurements are used to determine the various level points laid out throughout the country.

The first and second level surveys are called precision level surveys, which are the backbone of the national elevation control network, and the third and fourth level networks are spread all over the country, which are called national level points. On the basis of the national level point, for each project construction and engineering level measurement or topographic map mapping and map root level measurement, the same city for the general level measurement.

The principle of leveling is to use the horizontal line of sight provided by the level meter to read on the level tape erected on the two points to determine the difference in elevation, and to calculate the difference in elevation based on the readings.