New development to the pneumatic measurement technique

Non-contact pneumatic measurement technique is an important method in the dimension measurements of machine parts. For the traditional back-pressure pneumatic sensor, the measurement range (MR) is about 0 similar to 200 mu m with the measurement accuracy (MA) of 0.1 similar to 1 mu m. In the recent years, two new types of pneumatic sensors have been developed by the authors, and are introduced in this paper. One is called reflect-pressure pneumatic sensor with 4mm in MR. Its non-linearity is less than 2%FS. Another is called air-pin pneumatic sensor with 10 mu m in MR, and its MA is better than 0.1 mu m. The new techniques developed above have been used in the in-process inspection systems for the dimensions of train wheels and the sphere diameter of gyro bearing individually. They could also be used for automatic measurement of different machine parts in industry.