Improving the Measurement Reliability of the End Gaps of Piston Rings
Luhua Fu*, Heng Zhang**, Yan Sun*, Na Zhao*,
and Zhong Wang*
*State Key Laboratory of Precision Measuring Technology and Instruments, Tianjin University, Tianjin 300072, China
**National Institute of Metrology of China, Beijing 100013, China
By using an automatic piston ring separator based on advanced computer vision detection technology, the end gaps of piston rings can be automatically measured with high efficiency and accuracy. To get a complete and accurate image of the end gap as well as measurement reliability, the positioning of the end gap of a piston ring must be accurate every time it is photographed. During the loading process, a mechanical structure and pneumatic actuators are used to provide the correct initial position and guide the motion. The actuators also control the deflection of the piston ring and get the top surface levels of the piston rings evened up at the detection position to ensure the correct detection position and imaging object plane. This guarantees the quality of the images of the end gaps. Data compensation is carried out to decrease the system errors arising from manufacturing errors in ring gauges and increasemeasurement accuracy. Experimental results show that the measurement accuracy meets the demands well, and measurement reliability is good.
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