Measurement principle of pneumatic momentum meter
Time: 2022-12-16 11:24:25
Source: Luoyang Mingsheng Measurement and Control Technology Co., Ltd
The pneumatic measuring instrument is a kind of measuring instrument that can be assembled by multiple sets. It can be used with different pneumatic measuring heads to measure various parameters.
1、 Composition of air momentum meter
According to Air momentum meter Each component has different functions, and the air momentum meter can be divided into four parts: air filter; Air regulator; Indication part; Measuring device. 1. Air filter: the main purpose of air filter is to remove water, oil and inclusions in compressed air. When the compressed air enters the air filter from the air inlet, the water, oil and impurities in the air are removed by the filter device and discharged from the air outlet. The condensed water and oil can be discharged by opening the lower drain valve. 2. Air regulator: the function of the air regulator is to change the fluctuating compressed air into constant pressure compressed air to ensure satisfactory measurement results. 3. Indication part: the indication part is used to indicate the measured size for reading, and its main parts are taper glass tube, buoy and scale. In order to facilitate the manufacturing, adjustment and use of the measuring head, it also has zero adjustment and multiple adjustment parts.
4. Measuring device: the measuring device is directly used to measure the size of the workpiece, and its structure varies with the measurement requirements.
2、 Advantages of air momentum meter
1. There are many measurement items, such as length, shape and position errors. For some measurements that are difficult to solve with mechanical measuring tools and gauges, such as the inner diameter of the deep hole, the inner diameter of the small hole, and the width of the narrow groove, it is easier to achieve with pneumatic measurement. 2. The magnification of the meter is high, and the human error is small, which will not affect the measurement accuracy; There is no mechanical friction during operation, so there is no return error. 3. The operation method is simple, the reading is easy, the continuous measurement can be carried out, and it is easy to see whether the dimensions are qualified. 4. It realizes that the measuring head does not directly contact the measured surface, reduces the influence of measuring force on the measurement results, and avoids scratching the surface of the measured part, which is especially applicable to the measurement of thin-walled parts and soft metal parts. 5. Due to non-contact measurement, the measuring head can reduce wear and prolong the service life. The main body of the pneumatic momentum meter and the measuring head are connected by a hose, which can realize remote measurement. 6. The structure is simple, the work is reliable, and the adjustment, use and maintenance are very convenient.
3、 Measurement principle of pneumatic momentum meter
The measuring principle of pneumatic momentum meter is comparative measurement method. The air momentum meter is a device for measuring the length and size based on the principles of hydrostatics and hydrodynamics, using compressed air as the medium. The measuring method is to convert the length signal into the air flow signal, and the value is indicated by the buoy in the glass tube with a scale, which is called the buoy type pneumatic measuring instrument; Or the gas signal can be converted into an electrical signal through a gas electric converter, and the light column indicator composed of light-emitting tubes is called an electronic cylinder pneumatic measuring instrument. The air momentum meter can be used for non-contact measurement with high measurement rate. The pneumatic gauge is suitable for measuring internal and external dimensions in mass production, as well as hole spacing and shaft hole fit clearance. When measuring with a pneumatic gauge, it is necessary to match the corresponding probe according to the measured size. The pneumatic inner diameter probe has a simple structure and is suitable for hole diameter measurement. It can measure holes with a diameter of 1.5mm. The indication range of air momentum meter is small, generally ± 20~± 100 μ m. According to different indication ranges, the common graduation values are 0.5 μ m, 1 μ m and 2 μ m. The allowable error is generally not greater than one division value. During the measurement, the measuring head is not in direct contact with the measured surface, which not only reduces the influence of the measuring force on the measurement results, but also avoids scratching the measured workpiece.
4、 Measurement items of air momentum meter 1. Inside and outside diameters: The air momentum meter is often used to measure the size or shape of the inner diameter of the hole and the outer diameter of the circle of the workpiece. Two nozzle pneumatic probe with two opposite nozzle holes is usually used to measure the inner diameter of the hole, while the pneumatic plug rule of two nozzles is mainly used to measure the outer diameter.
2. Average: The measuring tool with multiple nozzles evenly distributed on round surfaces can measure the average value for users. This measuring tool is mainly used for thin-walled components or special round surface components. Four, six or more nozzles can be used. The number of nozzles will depend on the size of the measuring tool. 3. Roundness: extra round surface: The air momentum meter can measure the roundness of the workpiece. In case that two points are not round, two commonly used pneumatic probes with two nozzles can be used. In case of odd circles, the number of nozzles must be increased according to the number of odd circles.
4. Straightness: Another common use of the pneumatic momentum meter is to measure the straightness or bending of the dynamic measuring hole. In such measurement, the individual pneumatic probe can easily and quickly measure the straightness of the inner hole of the measured workpiece.
5. Perpendicularity: To measure the perpendicularity of a workpiece, for example, to measure the perpendicularity of a hole relative to a surface, the change of perpendicularity can be measured according to the change of back pressure by moving a pneumatic probe with a "Z" shaped nozzle in the measured hole.
6. Taper: The change of taper can be easily measured by air momentum meter through two different measuring heads with different nozzle face diameters.
7. Flatness: The flatness measurement is realized by moving the workpiece flat against a fixed plane with an air nozzle. In this way, the flatness measurement is fast, convenient, simple and accurate.
8. Slot width: The thin probe can easily measure the size of the groove. The air momentum meter can not only measure the width of the groove, but also measure the parallelism of the two sides of the measured groove.
9. Fit tolerance: For two workpieces with tolerance and fit requirements, the electronic column displays the dimension value of the hole, the dimension value of the shaft, and the clearance value between the hole and the shaft respectively.
