Abstract:  Aiming at the high precision requirement and the difficulty of testing the scroll profile of oil-free scroll air compressor, a study to analyze processing technic and testing technic of the circle involute of the scroll plate was proposed. Firstly, several samples on the scroll plate were collected at the same height on the vortex teeth using a high-accuracy trilinear coordinates measuring instrument. Then the equation parameters were estimated by geometric method and involute expansion angle was estimated of four selected typical samples. Then the accurate pending parameters of the profile equation were solved by the Newton iteration method and the error between the samples measured by the trilinear coordinates measuring instrument and the scroll profile was calculated. At last, the quality of the oxide layer by the hard anodizing was analyzed. The results show that the calculation method proposed in the study can solve profile curve with unknown parameters and assess the profile accuracy efficiently. The mean error and the mean absolute error of the measured samples are about 5μm and 20μm respectively, and the uniformity and the hardness of the oxide layer can meet the requirement. The study is significant to improve the testing process and quality control of the oilfree air scroll compressor.

Key words: oil-free scroll air compressor; scroll profile; testing technology; processing technic of scroll plate