Study on pneumatic measurement method and system for throttling edge coplanarity error of valve sleeve

The function edges of valve sleeve throttling orifice are required to have high precision coplanarity, and the coplanarity error is generally not allowed to exceed 0.002 mm in servo valve production process. The traditional measurement is only an approximately measuring method, whose automation level and measuring accuracy is too low to satisfy actual requirement. A new measurement method is put forward based on pneumatic measuring principle of differential pressure approach, and the automatic measuring system is developed according to the proposed method, which realizes non-contact and high accuracy measurement for throttling edge coplanarity error. The linear range of measuring system is determined by system calibration experiments and least square linear fitting method, and the actual measuring experiments for four groups of throttling edge are carried out. Experiment and analysis results show that the measuring error does not exceed 0.0005 mm and the pneumatic measuring method satisfies absolutely the measurement requirement of high precision for throttling edge coplanarity error.